You will usually clean it once a month is sufficient. If you notice slow draining or the washer gets stuck on a cycle many times that is indicative of the filter needing cleaning. Great idea to be pro active and glad you asked as many people fail to even realize there is a filter and call service unnecessarily.

They only make a downdraft range combo with the vent in the center. Jenn Air and Kitchen Aid make this option. If you 100% want it in the rear, then you can buy any slide in, and as long as you have the extra depth, brands like Elica Best and Zephyr make downdrafts specially designed to go behind a range. The issue is the motor will have to go behind it or in a basement remotely mounted, so the setup is more complicated to achieve and usually needs a much deeper cutout.

You paid attention to my posts and I appreciate that. I do love the 800. But with no dispenser, the 500 is decent. But to be honest, the GE Profile is a better unit. I get you need to stay in the budget, so even the baseline GE will be good. I have had some hiccups with the Bosch 500 lately. So I have kind of moved it off my list till I see them get corrected.

https://www.geappliances.com/appliance/GE-ENERGY-STAR-22-1-Cu-Ft-Counter-Depth-Fingerprint-Resistant-French-Door-Refrigerator-GYE22GYNFS

Unfortunately that is too short and they do not offer one. Whirlpool and KitchenAid make low profile microwaves model just under 11″  here is the link to the  Whirlpool Microwave WML75011HV

Whirlpool Microwave

Here is a list of all low profile over the range microwaves under 11 inches.
Low Profile Over the Range Microwaves