Multimhoming with BGP to 2 providers

Hi all,

I'm kind of new to multihoming and BGP on the internet so apologies if some of these questions seem stupid. My company recently acquired a /24 from ARIN. Currently we have 1 ISP for which we have a router that we manage. There is a /30 WAN block and a /27 LAN block on it of ISP provided IP's currently. We are in the process of getting a second ISP and a public ASN and my eventual goal is to do multihoming using BGP with both advertising our new PI space in addition to using the IP space they provide. A couple of questions I had are:

Should we have the current ISP statically route it temporarily until we can get the 2nd ISP and public ASN so we can start using it?

Should we use secondary IP address for this new LAN block or sub-interfaces on the router?

In either case should it be broken up into multiple smaller networks on the router (multiple secondary addresses/sub-interfaces) as that is how we intend to use it? for example a /29 for firewall Outside interfaces, a /28 for public DMZ etc.

Okay to use the same router for the second ISP or better to go with a new one and run some sort of iBGP between the 2? If its the same router then do we put the routes and interfaces for each ISP in different VRF's?

Any help would be appreciated. Thank you.