@BrandonS
For some reason I didn't realize that you had two ISP providers. Thought we were talking just one here.
If your only using 1 switch, then each MX should only have one connection (since they don't support LACP).
The diagram your showing is if you had two switches.
You don't need a specific VLAN for warm spare. By default the VRRP packets are sent out on all vlans.
Each ISP would need to give you 3 IP addresses (this is only done by giving you a /29)
As for the edge switch between your ISP and your MX, I believe this will be needed unless they are able to hand you 2 uplinks from their side for each ISP.
You can use your core switch for this too if you want. Via that diagram from https://www.willette.works/mx-warm-spare/
Keep in mind doing this now makes that switch a single point of failure.
As for the vIP, if you get a /29, you actually get 5 usable IP addresses. So you use two of them for each MX and then one for the vIP, entirely up to you.
As for your client-VPN, if ISP 1 goes down, even using the vIP, then I would imagine you lose your client-VPN even though ISP 2 is alive. Maybe @jdsilva knows if that DDNS he mentioned earlier solves this?