Confusion on ILM policy and please help me to understand it

Hi Team,

I am working on a system where I expect daily I am going to ingest a data about 15 GB and my total retention of data should be about 365 days. However my active data would be about 1 month of indices. After 1 month data can be moved to warm and after 60 days it can be moved to cold.

Please help me to understand my ILM policy since I am very much confused on designing the policy.

Hot Phase -> Enable Rollover
15 GB
Maximum age 1 day?
Do I need to go for Force merge & Shrink in Hot phase?

Warm Phase
What should be value here? 30 Days?

And same way what should be the cold phase
90 Days?