First of all, I'd jump all over that trade. In fact if you have a veto system I'd be worried about it getting knocked down. You're selling high on Shields whom a lot of people think will regress a fair amount, plus Bud Norris and Howie Kendrick, neither of which I'd lose sleep over. Wheeler and Martinez both have ace upside but you'll be lucky if you get a #2 SP and a good closer out of them. Pitching prospects are even more volatile than MLB pitchers. Those are two nice guys to have in a dynasty but look at what you're getting in return: Kemp is 27 and a top 3 player. Beltre is really good and fills a hole at 3B. Zambrano, Schierholtz, whatever, but Josh Bell has insane upside and if Lavarnway works out, you'll have C covered as well.
Point of the point, jump all over that trade.
Of your bench players, I'd keep:
L Cain - nice upside, should be a starter this year.
N Eovaldi - young pitcher, intriguing minor league history, take a shot
C Perez - saves are saves
The others I could take or leave. I know you can keep 7 of those, but for the other 4, well, flip a coin? No real attractive options. Bourgeios has some SB potential. John Jay is starting, right? These are all pretty marginal players.