Dition: 1) There really not that much race-based dialogue options/answers and even then they're not significant in any way. IIRC, the DF has the most of it with Humanis racism and whatnot. So, the troll is as fine as any other race. When it comes to character build... There aren't any exact tanking mechanics in place - it's more the matter of you choosing to be stabby/shooty street sammy, who combines martial proficiency with a lot of health (or lack thereof, should you not invest in the Body). The only thing that I would advise to do in order to see as much in the games as possible is to boost your charisma to gain 2-3 etiquiettes - those are quite important (especially later in the series).
As for rogue... There is no stealth system to speak about. However there are sometimes situations where you may try to go for infilitration instead of outright assault (still I can't remember any outright sneaking involved with sole exeption of controversial change to Matrix in HK).
Only other advice - you may want to look into bringing decker and mage with you on the appropriate runs as they may provide additional dialogue options as opposed to purely martial characters.
2) You crate only main character - everyone else are pregened. Now the party managment itself... It depends on the game. In first one, SRR, you hire other runners for money you have at the moment or their share of everything you find during mission. On a few occasions you will be able to hire people for free because of their personal reasons (not that their presence is extremly significant). So you basicaly hiring mercs to do what you can't. In later games, however, you have crew of characters who run with you for free in addition to already established "rent-a-runner" system. Their use is prefferable due to them being part of story, providing insights and their dialogue being overall one of the better parts of the games and due to them rolling with you free-of-charge.
And yes, you control all their actions with the oblivious exeption being them chatting with you. So you will experience the Matrix no matter what.
3) Well, almost every character build will finish the game without a lot of trouble and expirencing game content more comes down to your willingness to do additional runs, speak to other characters and other things like that. I can't even name one thing that you may miss by not being mage/decker. There may be a bit more blood on your hands, a bit less money on creditstick and a bit less things heard - but this isn't really tht much that you'll miss, IMHO.
Oh, and BTW. My decker/face character in HK? By the end of it he tore most enemies apart with some nasty chrome. So it isn't impossible to do a lot of things with just one character. Hope you'll have a blast with the game, chummer.