Buying properties with tenants in place - what do we ask for?

Tenancy Types and Management

We are hoping to buy 2 adjacent properties, one with a tenant in place (been told they are 1 month into 6 month AST) and one about to vacate. Due to time lag in sale going through, with the latter property the current owner is planning on reletting, with us having a say in tenant.

Having had a quick look on here it seems possible to transfer ownership mid-tenancy?

Can anyone give me advice on what we need to look out for?

I will need to see agreements to make sure I am happy with them, also make sure deposit was correctly protected. What happens to that? Can I ask for it to be redeemed and transferred to me and re-protected?

I assume I need new rental agreements?

The estate agents are also letting agents - are they likely to sting me for fees for taking tenancies over?

Many thanks.