I've been playing nfl.com's FF for four years and find it is imperative to be able to start two solid RBs on a weekly basis. If you draft RB in the first 2 rounds you will end up with 2 top 10-15 RBs, also draft your back up RB early because it really hurts to lose a starter and this is the toughest position to replace once the season begins. You can usually let the QB position slide a little because the drop off in level of prodution isn't as steep as RB and as stated in an earier post you only have to have 1 QB and 2 RB. WR is very deep and you will usually see some bargains slide into the later rounds. But if you want one of the big names you will have to take one by the third or fourth round. I do advise this because WR aren't as consistant but there are a few who are very consistant as far as WR go. Don't worry about K and Def until the last few rounds. You can usually get a decent K off free agents and Def is to close and there are usually a couple of them that slide. As far as drafting back ups to players (Mack for Taylor, ect...) I don't advise this stratagy because in an auto draft you have know control once the draft starts so you may get the reserve but not the starter. Besides that you can most likely pick him up after the draft. Also back to QBs, If you do let that position slide a little late in the draft I find that drafting them back-to-back is benificial. With that said here are a couple of stratagies I would consider, one letting the QB slide (which is normally the way that I draft) and one taking a QB early. After the draft I suggest that you only carry one K, TE, & DEF unless you end up with to very highly rated players. At these positions you will be better off picking up more depth at the skill positions especally RB. If you end up with an abundance of RBs they are great trade bait because there will alwys be someone in your league that needs an upgrade or has to compensate for an injury. As far as taking care of K, TE, & DEF bye weeks just wait until thier bye week and get the best possible free agent and release your least valuable reserve.
I hope this helps.