HA/VRRP - OSPF/BGP routing behavior

I have a design for a resilient and secure HQ internet. I will be running the following routing protocols

eBGP to provide dynamic failover for fibre cicuits (CPE / ISP)
iBGP to provide dynamic failover for local WAN fabric (CPE / B310X)
OSPF to provide dynamic local routing (CPE / firewall / B310X)

I will be deploying two Peplink B310X configured in HA.

What I would like to know is how B310X VRRP stack operates on failover/failback with regards to:

  • OSPF and BGP - neighbor and peering establishment, routing table entries
  • WAN interface/routing priority selection
  • Data routing downtime during failover
  •   PepVPV tunnel downtime during failover

Also, can you recommend which production firmware is best recommended to support this design.