First off a treaty doesn't subtract anything from you. It just gives the possessor 10% of your base econ income/research, and that is created out of nothing....
I usually wait to hand out treaties after ~2years 2 months, because around that time, the AI is considering to give out treaties as well, and I'll take other treaties for it. if you play a peaceful game, try to get as many as possible, esp. the tech ones are easy.
theoretically you could give your own out much sooner in order to prepare an early alliance.. but the AI doesn't pay much for them in techs or bcs, and an alliances also isn't possible before 2 years 2 months....
if you wanna max the worth of your own treaties go 100% research & raise taxes to 100%, and use spies on all econ & research buildings your partner has... the value of the treaties will change right instantly even during the turn.... that is, after the barter return everything to normal
re: Dreadlords
try to rushstorm their colony as fast as possible, colonize planets mostly to gain range. Dreadlords usually wait some time in order to fill up their planet only with factories, and release a light ship here and there, but if you bungle it and need too long, once a frigate blocks their way you don't have many options left.
one is to go for maximum speed and build superfast ships that lure his strong ships away, circling around the galaxy... while you wait for a chance for their planet to be defenseless so you can storm him...
if you struggle to survive... or need more time to do research.... go for maximum populated worlds 15-20b and invest into soldiering alot. prepare to destroy a planet if they come with too many troop ships at once..