Lots and Lots of level 30 Marauders, don't bother wasting pearls on any thing else until there maxed, unless you want to try and compete with the Mega Coiners in which you better do the lottery ever week.

Depends on who ye be attackin'!  'rauds be slow but they are the best bang fer the res investment.

imo the best method of troop productions is to build mostly offensive units.  Whatever is quickest for each que.  Sacrifice them on prizes and keep growing your other troop types until you have something to work with.  Then use whatever troops you do not need for prizes against other players should they motivate you to do so.

I build mostly offensive units because at some point the resources are not as much of a barrier as the production times.  If a marauder costs more than a bonnie to build, has double the power rating, and produces in the same amount of time then when you sacrifice it on a prize you get back a better reward for the time spent in production.

I'm sure market research was done and there is a reason for the imbalance of power between the two.  I personally feel that defense should produce in half the time of their offensive counterparts since we have to use twice as many of them on the defensive missions.

Work hard on your sketches.  Trade for them, ask for them, research them.  The faster you can get to all levels of production the better.  The higher the level of your troops the more you get out of your productions.