Dust collection is a big deal. The most important thing is that you trap and collect the dust at the source, and a simple 2.5 inch port just behind the bit, attached to a decent dust collection system. Here's a picture of the Rockler device for that, but it's the same as ones by several other suppliers.
I have a metal box (Rockler) under my router with a 4 inch connector at the rear. It feeds directly into a Y connector with 4 inch and on the Y, 2.5 inch which connects by hose to the behind the fence fixture shown. A T connector isn't as good because you lose air flow with each 90 degree turn in your DC system.
The box under the table has a simple air flow control valve. You have to allow air in or the sawdust simply packs down without being extracted.
All my dust collection parts are Rockler because 4 inches seems to be different when you try to mix suppliers.
All my dust collection is extracted by a 4 inch flex hose from Rockler. It's about 25 feet long and will reach all tools in my shop. I don't have the space to put in fixed tubing. The hose goes through the wall into a small chamber where I have a 30 gallon chip collection drum with a Super Dust Deputy on top. Almost all dust and debris falls out into the drum. The rest of the air is pulled into a Harbor Freight DC unit with a 1 micron drum filter on top instead of the stock 5 micron bag. The air is filtered, then passes through another filter, back into the shop to preserve the AC or heated air there. Here's a picture of the inside of the DC chamber:
There's almost no dust in the clear plastic bag, in fact, if there is, it means it's time to empty the chip collection drum. This whole setup costs about $600 to set up (Look for 25% off coupons from Harbor Freight). Here's what that looks like in the chamber.
Here is a minimal setup that is easy and fairly cheap to put together. The Dust Deputy cyclone is what separates the sawdust and chips so it doesn't clog your shop vac filter. Get the biggest shop vac possible if you are going to try to collect dust at the fence AND under the router.
Osha did a study that was pretty disturbing to any of us with breathing issues. The average commercial woodworking shop had very low levels of sawdust in the air. Home shops, on the other hand, had dust levels far above the danger level. The problem is the really fine sawdust that once it gets into your lungs, is never expelled. Lots of old time carpenters and woodworkers died gasping for breath because of this.
Spend whatever you can on good sawdust collection, it's as important as keeping your mitts out of the sawblades.