Super top-up health plan: multiple queries

I am 39M with some pre-existing conditions. Considering Super top-up health plan to cover for low probability high cost treatment. Thinking 50L coverage & 5L deductible, with no base plan. Few queries:

1. I plan to pay deductible out of own pocket, without relying on a base plan. Is this possible or having a base plan is mandatory to buy a super top-up?

2. If I do above, do Insurance companies create problems/hassles in accepting that deductible has indeed been paid? Of course I will need to provide all bills & payment receipts, but trying to find out practical difficulties.

3. Is cashless even possible with super top-up? I am hoping that paying deductible out-of-pocket will make it possible, as base plan will be out of picture.

4. Is the deductible applicable separately for each policy year?
   Example - assume policy is for 01 Jan to 31-Dec-2027 and will renew on 01-Jan-2028. With 5L deductible, I make 4L expenses in Dec 2027 and 3 lakh expenses in Jan 2028. So total 7 lakh expense, split across two policy years. Can I claim super top-up reimbursement of 2L (7L - 5L deductible) in Jan 2028?

Thanks in advance!