I Need help :/

I'd suggest going directly to t6 since it costs less and adds more stats

 

I'd personally go for the t5's first and build up your plunder. I'm really not sure however the plunder difference in putting in a t6 instead with them being relatively new.

 

Yes but when you have all dorms with t5 your stats will be lower as opposed to dorms filled with t6.

 

Do it like when u change t4 to t5. T5 to lvl 2 in all dorms, then u convert to t6. Simple