1. I have dwarf sag in there and it's spreading quick, should i hold it back, or is it ok if it spreads a lot?
I would let it spread, get your shrimp and fish established, then worry about messing with it.
2. I just ordered the fish for the tank, should be in thursday - bororas brigittae :). With this order I got 30 alder cones to round the price off. Would the fish and RCS benefit from these? Otherwise I will just sell them locally.
I would sell them, unless you like how they look. There is no direct benefit that I can see from them
3. The assassin snails have been doing good taking out the pond snails, should I remove the empty shells? or are they ok to stay
Take them out, they can harden the water when they decompose.
FW: 1 45gal, 1 40gal, 3 10gal, 3 30gal all community tanks of different species
Sw: 1 55gal, 1 30gal show, 1 29gal show, 1 20gal and 2 10's