Welcome to LRH,
First, if you're interested in LR shooting/hunting, then I would recommend heavier, high BC bullets for the 300 WSM. The minumum weight I would consider would be the 180's.
Here's a list of a few..
180 gr E-Tips, AB's
180 JLK VLD/LBT
185 gr Berger VLD
190 gr Beger/JLK VLD/LBT
200 gr AB
210 Berger/JLK VLD/LBT
I personally would shy away fron the more frangible Begers, JLK's and AMax's for closer range shots.
Two powders you might try would be H4350 and RL17. H4350 is a good consistant performer and temp stable. I found RL17 gave 200 fps more with 180 bullets than H4350 in *MY* rifle. Not sure about RL17's consistancy and temp sensitivity yet.
With 180's you want to start at about 60 gr and will probably find max at about 65-67 gr.
With heavier bullets, start a little lower and work up. Always work up no more than 1/2 gr at a time as I have found out the hard way
Sorry, cant help you on the 150's.. haven't used them.