The MiktoTik switch/router CRS326-24G-2S+RM ( https://mikrotik.com/product/CRS326-24G-2SplusRM ) can use either
SwOS or RouterOS. With RouterOS installed, can it be configured to have more than 1 WAN port
for Load Balancing the WAN traffic? If yes, do I need to change it from current Bridge Mode to Router Mode?
Or is a separate dedicated Load Balancing Multi-WAN router a better solution? Does MikroTik have such products too?
All Mikrotiks run the same Software, either swOS or RouterOS…
swOS can be used on Devices that will do Switching, and thats it…!
For routing purposes you use RouterOS… If you want the device to load balance multiple WAN interfaces you must notice that CRS Series are Router-Switches that have limitations on the Routing Part…
So it is up to you to choose the correct device… On every products page you will find a “Test Results” section that shows the performance of the Device…
… but while looking at those numbers, don’t take the biggest one as relevant for average real-life use. Many of us on this forum find the number in “Routing - 25 ip filter rules - 512 byte packet size” quite realistic. If router is configured optimally (sometimes is just too easy to mess the config a bit too much) and if one doesn’t exaggerate with number of firewall rules.
This switch is good if you want routing inside your LAN between subnets [VLAN] BUT it is not very good if you want to do WAN to LAN Routing. So from a switching perspective - YES it can switch at wire speed but cannot route at wire speed.
If you want to route at wire speed on the switch YOU will need to look at other brands.
My suggestion is if your network is small …i.e. less than 100 users … then get a good router like the RB450Gx4 and combine it with the CRS326-24G-2S+RM switch and that will be an excellent combination.
You will need to identify your needs properly to be able to get the right gear.
Inter-vlan [sub-net] routeing is a very good idea when the SWITCH in question can effectively handle the load and the load all depends on many factors.
Yes the CRS326-24G-2SplusRM can have as many WAN connections as you may desire BUT the performance will be poor.
If you want to route at wire speed on the switch YOU will need to look at other brands.
Route at wire speed on the Switch ? 
What is that supposed to mean? A switch is a switch, it does not route Traffic…
The CPU takes part in the Routing Process…
Yes, Multi-layer-switches can route at wire speed - MLS …
There is no performance difference between forwarding at different layers because the routing and switching is all hardware based – routing decisions are made by specialized ASIC with the help of content-addressable memory.
http://etutorials.org/Networking/Lan+switching+fundamentals/Chapter+6.+Understanding+Multilayer+Switching/Introducing+MLS/
Thanks, I didn’t know this device. Its specs (4-core CPU, 1 GB RAM) and the test results are promising, it also has an attractive price tag of $99 plus case, as it’s just the board.
https://mikrotik.com/product/rb450gx4#fndtn-testresults
Yes, Multi-layer-switches can route at wire speed - MLS …
A multi Layer switch is just a Switch with Layer 3 capabilities…
And am sure their traffic passes the CPU before reaching the Switch…
A MLS Switch has a dedicated cpu for routing and a dedicated ASIC for switching plus it has Flow Control that determines who gets what like a special cache management system … it works on 3 layers … L2 L3 and L4
https://en.m.wikipedia.org/wiki/Multilayer_switch
Multi-layer switching combines layer 2, 3 and 4 switching technologies and provides high-speed scalability with low latency. Multi-layer switching can move traffic at wire speed and also provide layer 3 routing. There is no performance difference between forwarding at different layers because the routing and switching is all hardware based – routing decisions are made by specialized ASIC with the help of content-addressable memory.
MikroTik do not make MLS Switches … maybe one day they will at attractive pricing … MLS switches are expensive.