first and foremost, 75% of your answers are here.
http://www.buzzerbeater.com/community/forum/read.aspx?thread=144856&m=1
for salary estimations i suggest using buzzer-manager.com salary tool section. a lot of nifty tools will be availalbe for you to better grasp the sensitivities of the game.
does not matter how mild of a take someone will give on the forum, taken out of context of experience you will extract little info from it.
for example, i can tall you right now that rebounding is very expensive skill to own, but that only applies from one point onward. conversly OD is the cheapest and most overpowered , that is a mainstream valid view, but it is not really easy to train in ways that give you an edge.
what is important is that you asked yourself design questions as to how to shape your team.
to spare you the time wasted i can tell you right here and now that unless you have an excelent 18'old prospect that you can train, whatever team you will have in div 4, will be revamped in div 3 and so forth.
this game has several components : tactical, financial and team building. lacking in one of those areas will keep you down. but generally, irrespective of country, if you have a medium to large user base at the beginings and lower leagues amassing more assets and better players based on raw skill will suffice to get you out of D4, maybe even D3, but unless you have adequate team building strategy in place you may promote fast and hit a wall in d2 or even relegate without a chance.
so. set a goal. ask around what is needed to achieve it in order to put in the discipline and effort into amassing assets/value, while also gaining tactical experience. d4 and d3 are the wild west in that regard as financial limitations make it unlikely to encounter high level players/NT, at best some u21 players. so try anything.
Look inside is the most used tactic in this game but if you use it too often you will be guessed/predicted by opponents and may shut you down, so being able to use a complementary neutral tactic will help. some tactics need more players to be effective, such as pricneton where you need outside shooting on the interior as well, others suffice with just one offensive player in the right circumstance (patient, inside isolation, outside isolation etc)
so to recap
1. whatever you like. depends only on the personal available to you. even if some tactics seem more effective remember the being unpredictable limits the use of predictions against you. but be unpredictable and effective.
2. defence is specific to elague. in d3 prolific(11) defence on all positions represents the bare minimum. in d2 tremendous 13 and d1 15 marvelous.
and by minimum i'm saying that the given players may be brilliant offensively but if they lack in passing that will kill your team success. also, depending on the league you are in, as is the case in the US, some numbers may be need to be higher.
good luck and use the forum but also try to read up more.