Leveraging a Job Offer

Hello all,

I'll try to keep this short but include the relevant info. Never moved jobs before so I would like some advice. 

• Job A: I am currently at a job that I like, but am underpaid (in office 100%)
• Job B: Receiving an offer from another company for a similar position this week (pay is 25-30% higher, fully remote)
• Job C: Waiting on a third position that I REALLY want, but not sure if/when I will receive offer (35-40% higher than original position)

A few questions:

1. How do I tell Job B I would like to think about the offer they present, and stretch the time for as long as possible without being over the top? 
2. Can I reach out to Job C and let them know I have an offer from another company but I would like to join them? 
3. What is the best way to go about asking my current company (Job A) to match (at the very least Job B). 

Apologies for the basic levels of questions, but I have just never had to do this before. Thanks all.