Hi, I have just bought a RB1100AHx2 to power our company's network.
This is my first tour with RouterOS so please forgive me for any silly questions.

We are given 5 IP addresses by the ISP, let's say they are 10.10.10.2-6/29, and the gateway is on 10.10.10.1.
I'm using the ether13 as the WAN port and assigned these 5 IPs to it.
And we have 2 local subnets: 192.168.0.0/21, 192.168.8.0/21.

Question 1: How to make the 2 subnets both be able to access the Internet, preferably with 2 different public IPs?
(I think I should create 2 src-nat rules to achieve this, correct?)

Question 2: Suppose I have a VPN device already manually assigned one of the 5 public IPs (let's say, 10.10.10.6), thus if I plug the ISP cable into it, it can directly access the Internet. The question is how can I connect this device to RB1100 as if it is just directly connected to the ISP cable?
(Should I bridge another port with the WAN port to achieve this?)

Thank you so much for help.

Okay, i'm not sure i'll be able to help you here but first lets clarify the question.

so you have a /29 network that has been given to you by your ISP with a gateway of 10.10.10.1
Can i assume that gateway is a router provided from the ISP?

Now you say you've added all five IPs to the wan port, port 13.

I'm guess the two local subnets are on other ports, lets say port 1 and 2.

so moving onto Q1.
You what the two subnets to access the internet using these IPs.
Are you saying you want one local subnet to access internet via one Public IP using masquerade and the other local subnet to do the same with another public IP?

If this is the case then this is difficult. I have an idea as to how it may work but i'll need to test it first, and discreetly. If i make a mistake i could piss off a lot of people

Q2
this bit i don't fully understand. could you explain more as to what you have done here.

okay, a bit of testing later and i hit the wall i thought i would. I was trying to see if i could get round it but no luck.

The way i see it, if you want to do what you're asking you're going to need two routers, each one handling each network.
either you could get the two routers or just visualise the two on the one you have right now.