Welcome to the board and (hopefully) to the game.
NeoTanuki wrote:...the KR (the Romulan version of the D7 battlecruiser).
Actually, the KR is the Romulan version of the older D6 heavy cruiser. They are externally essentially identical and very similar in gameplay attributes, but folks around here take their Star Fleet Universe (SFU) history very seriously.

The Klingons had dozens of D6s in storage as reserves and sold what was obsolete ships to them to the Romulans (who were coming out of the non-tactical warp "dark ages" and the D6s were a quantum leap for).
NeoTanuki wrote:1) Between the D7 and the KR, is one more effective or easier to learn to play?
Neither is dramatically more effective than the other. The D7 is a newer and meaner ship (it was the Klingon replacement for the D6 the KR is converted from), but the difference isn't huge. It could be argued that the D6 and KR would be more "even", but Klingons and Romulans aren't particularly suited to fighting each other in the SFU so any comparisons start to get shaky.
As far as ease-of-play, any Klingon will be easier than the equivalent Romulan, due to the weapons used by the two empires. The disruptor is a fairly easy weapon to learn (if not to master) and the Klingons don't use enough drone missiles for it to get too confusing. Both Romulans and Klingons use phasers (just like every other empire), but the Romulans tend to use the better phaser-1, whereas the Klingons cheap-out and use phaser-2 mounts most of the time.
The Romulans are more difficult for some folks to master, due to the interactions of using the cloaking device and plasma torpedoes. Both empires tactics tend to reward patience and subtly, but it is a requirement for Romulans. They tend to have only one "big gun" plasma launcher and it takes
forever to arm - that's why they have the cloak. Trying to "close and hose" with a Romulan having no torpedo ready, against a matched opponent rarely ends well for the pointy-ear folks.
NeoTanuki wrote:2) Would you say they are equal in performance, if not what are the strengths and weaknesses of each? (If they're equal, I may just go ahead and try the Romulans!)
See-above. With equal skill-levels/experience of players, Romulans and Klingons work equally well against their natural enemies (Federation, Hydrans, and Kzintis for the Klingons; Federation and Gorns for the Romulans). Pit them against an "un-natural" opponent (such as against each other) and your mileage might vary some.
Both favor the "long game". If you prefer short-term, roll up fast, take his shot and then "hit them with everything you've got" type ships, you'd be more interested in the Federation, somewhat the Gorns and Kzintis (depending on tactics), and especially the Hydrans (who excel at the close-up body-blow).
NeoTanuki wrote:3) As a potential new player with no experience, which set would be better to learn and teach other new players with: Academy, or one of the "Border" sets? (My friends and I have experience with light to medium tabletop mini and wargames, but none of us have tried the Star Fleet series of games. And how "teachable" is the game to people with no wargame experience?
FedCom is
very teachable to those who have prior experience with things like WarHammer, BattleTech, OGRE, etc. My friends with similar backgrounds had no big problems grasping it by mid-game in our first attempt. They had more problems "unlearning" their "Trek" expectations from 20 years of unrelated movies and tv than they did from learning the game-mechanics (Klingons in the SFU are
nothing like the unrestrained berzerkers they became in TNG; they are the brutal swarthy Soviet-analogues of the 60's tv show).
The game does fairly well for those with no "war game" experience. My wife (who had played Risk and one game of OGRE with me) had it figured out by a few turns in and promptly nearly defeated me. She needed more coaching, as things like "counters" and hex-maps were all totally new to her, but she did well, despite my poor teaching.
The game is the same between Academy and the two border boxes (literally, it's the same rules booklet). The only difference is the mixture of empires and ships the product contains. The two border boxes each present either Klingon or Romulan opponents to a mixture of Federation ships, with a mixture of supporting-cast empires (Kzinti, Gorn, Tholian, Orion pirates, and general-purpose ships like freighters). There is no overlap in the ship cards between the two border boxes, so they make great expansions to each other, but either one is a very complete game in itself.
The only reason to get Academy is if you are budget conscious. Last I checked, the border boxes are $60, which is an investment for some folks. Academy is a much smaller (and therefore cheaper) entry product. It only includes four ship cards (but the cards are the most recognizable "tv ships") and uses a paper map and the 1/2-inch counters, instead of the nifty mounted 2-sided map panels and computer-art 1-inch counters of the full-size border boxes.
Academy is a complete game, but it is only a very small taste of what is in the larger versions. I've bought three copies of Academy over the years, one just to cannibalize for "loaner" components for big game days and two as enticement gifts to friends I wanted to make into gamers (successfully, I might add).
If you choose to go the Academy route, there are "... Space" products that you can buy later, to get all the other stuff from the relevant border box that didn't come in your Academy folio (making your set into the same thing as the border box).
Don't forget the Boosters. These are a cheap way to get ship cards for the game (and duplicates of the really popular ships like the
Constitution-class cruiser, D7, War Eagle, etc.). There are also tons and tons of free ships up in the Communiques in Commander's Circle. Between the free downloads and Boosters, you can make Academy into a lifestyle choice, without ever even buying a border box.
NeoTanuki wrote:4) I have played the old "Starfleet Command" series of PC games, which I understand is based on SFB, and really enjoy them, if that helps. In that game, I seem to have more ability at playing the Klingons, more's the pity...Romulans are cool...
Starfleet Command was indeed based on SFB, at least in the design of the ships, the way weapons work, and the background. Changes were made to make it into a "real-time" computer game, but a whole lot of what you learned there will apply directly to FedCom (and SFB, and Klingon Armada, and any other ADB SFU game). A Federation New Light Cruiser (NCL) is essentially the same, regardless of what game it's being depicted in. The same amount and mountings of weapons, the same amount of power to work with, etc. Because of that consistency, tactics also tend to work across with various game (with adjustments).
I hope this helps some!