Mike , doing the under side repair I would grind back quite a bit , then layer about 3 layers one being a bit bigger on each over lap about an inch all around , and you might want to find a fiberglass roller to work out the air bubbles .

same with the top repair , grind back a ways from the cracks , then lightly V the crack area , then pull the fiberglass matting apart and dip it in your resin and using gloved hands put it in your V groove repair area , then cut a few thin strips and lay over the top , shouldnt need more then 2 layers over this repair . and then roll your fiberglass roller over it to smooth out air pockets .
Let set up and lightly shape with a 3" grinder . then use filler , sand and prime .