1) Who would remove the guy’s skin tight speedos and how would they remove them?
Sweeney would probably just tug and pull them off.
2) What would Mrs Lovett. Think of what had been in the trunks when Sweeny hands it to her .what she do with it then?
She would notice the large size, and perhaps comment on it. but her main concern would be getting 'meat' for her pies, so she would then toss it into her pail to be cut up.
3) What will Sweeny do with the parts of the guy that can`t be used in the pies?
To decrease the chances of getting caught, he'll want the bones, etc. to be well-hidden. I suspect he would first burn the remains, then cart them off to a secluded area at night, and bury them.
4) What will they do with the guys blue swim trunks?
Burn them to be rid of all evidence.
5) When Sweeney returns to the barbers shop to tidy up, what will he find in the changing area, were the guy got ready, what else will he find in the guy’s holdall?
He'll find the shirt, trousers, jacket, shoes, socks in the changing area. In the holding area, he'll find the guy's wallet.
6) What will he do with the stuff he finds in the changing area?
He'll burn all the clothing. He'll check the wallet for money and take any he finds, then burn the wallet, too.