How to understand routing table on merlin

[jacbao]

I have 2 WAN port, 1 is my primary internet access, another WAN only route traffic by specific subnet.

here is my route table:
jacbao@RT-AX86U-5E60:/tmp/home/root# ip route
default
nexthop via 100.66.0.1 dev ppp0 weight 3
nexthop via 10.125.20.113 dev eth4 weight 1

10.125.20.112/28 dev eth4 proto kernel scope link src 10.125.20.118
10.125.20.113 dev eth4 scope link
100.66.0.1 dev ppp0 scope link
127.0.0.0/8 dev lo scope link
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.2
192.168.50.0/24 dev br0 proto kernel scope link src 192.168.50.1
239.0.0.0/8 dev br0 scope link


I'd like to know:
1. is "default next hop" means default route a.k.a 0.0.0.0/0.0.0.0 ?
2 if so, how to delete default route to 10.125.20.113 ? and change weight to 100% to 100.66.0.1
3. what's means of "dev", "proto kernel", "scope link"?

I use Cisco router for many years, and newcomer to Merlin
is there any post or topic introduce "ip route" command?

btw, how many routes that merlin can support? I want to set 200+ static route, is that workable ?