Trial & billing question

I am planning build apps for some of my clients

Q.1 - Is trial available for every team separately ?

Q.2 - I might use my card info for many clients, so if I request refund, will glide accept separately for every team?

Q.3 - Some of my customers need heavy usage for few days in a year (events like summits), So if I use business plan for 7 days will I be charge of 7 days business plan & rest 24 other days of other plan like pro?