Skill Level Up Question

Here's my two cards:

B+ Bunyip lvl14 Critical rate up 1
ATK 1320 Def 1729 HP 2248 BP 14

B Skeleton Dragon lvl 1 Critical rate up 1
ATK 1112 Def 1213 HP 1091 BP 18

Should i just sacrifice B card into B+ since it's leveled up already OR sacrifice the B+ card into the B card being it has high stats at lvl 1 and cand be leveled up and have possibly better stats then B+ card.

Still trying to get the hang of all this. Secondly i have a B rank Poison Spit Frog. Venomous Breath (1)
Can you put that skill on a card with no skill or do you need to put it on another card with that skill?

Lastly i have tried to put a lvl 1 B rank card with Increase Party Defense on my lvl 14 B+ rank card and it didnt work the first time. I just got another card and is their something different i need to do?

Thnx for any help.

Save them both and use them on an A+ when you get one. If you're new to the game, please know that A's and A+'s come quickly... just be patient.

You can't change the skill of a monster, whether he has one to begin with or not, by sacrificing a monster with a different skill. But, there are skill cards in the game. They are kind of rare, but you can use them to change a skill, but not sure if you can add one if one does not already exist.

Thnx for advice. i've been holding off after first failed skill lvl attempt. i got a good bit of A rank cards. I'm happy with my setup so far. Just looking for more info on skill leveling. I just hate making stupid mistakes. More info the better.