Hi welcome to Binky Bunny! Have you already bought a cage? You can make some really nice ones of your own using NIC panels (wire cube shelving) and they are very versatile with many levels/floors that work great. Check out COOL HABITATS above under BUNNY INFO.
As for which sex is easier to cope with, I would say it is the same with both of them as they both are a pain when hormones kick in. However, you can neuter boys sooner than you can spay girls. So you might base your decision on that, although I woudl really hate to see anyone make a choice based on that. Have you thought about adopting a rabbit from a shelter or rabbit rescue that is already fixed? I think that woudl be ideal, not only do you save a rabbit from euthanization, but you are also helping shelters overcrowded with animals PLUS you get to see what their real bunny personality is after being fixed. : )
That is great you are planning on giving your bun room to run, and you’ll want to limit the running space and gradually increase it to perfect litterbox habits and reduce the amount/occurence of territorial pee & poo which can be frustrating. Definately check out BUNNY INFO above, it’s got some great tips, including BUNNY PROOFING.
A house rabbit is a definate lifestyle change and they can live up to 20 years. Be sure to check for allergies to rabbits & hay and I know this sounds utterly silly, but sit or crawl around on your floor to check for tempting bunny naughtiness. They really like to pee (mark) the bed and couch, as those are places that have your scent the strongest, so it is probably best you keep those places off limits unless the rabbit is fixed (sometimes that doesn’t help).
Lettuce is O.K. for rabbits except iceberg, it has very little nutrional value and it should be passed up for say romaine instead. You will want a good quality timothy-based pellet and you are right, pellets with dried veggies, colored bits and fruits are not good for your rabbit. Besides, fresh is much better in moderation with the fruit too. Check out DIET under BUNNY INFO. There is also a link to a complete list of bunny-safe veggies.
Also check out http://www.rabbithaven.org, http://www.rabbit.org, http://www.saveabunny.org for more info.