does this mean that the high the lvl the less possibility too lose ships and higher possibility to gain goodies?
also on the terran you send a science vessel to help
on the xerj you send a queen to help
is there a toss ship that helps in expeditions?

Investigators, Maybe

thats very expensive compared to queen or sci vessel 

Yeah ,right, 150 000 vespene. But that is the only way.

150000 vesp and lvl 8 expedition and ironwood (which you can only find not build) 

ps i just realized each time i have answered i have used i different account
shane is my terran, chicken is my xerj and enahs (shane backwards) is my toss

If you are same, you can sell science vessel and Queen from Chicken and shane version in dendariam or bestiary. make sure you will be the one to buy it