Walls – Drilling a hole as near as possible to a corner

Your instincts sound right. Be sure the drain tube is slanted downward as it exits. Also be sure the outside end of the tube will not be blocked (by leaves, snow, etc.) and that there is adequate drainage away from the outlet site. The ground should be pitched away from the wall (as in every foundation).

The likelihood of rebar or wiring within the cinderblock is very small. To be certain, go slowly and inspect with a light as the pressure changes in drilling. There are hollow sections in concrete and cinder blocks and you should be aiming for those, rather than the webbing between holes.

Sealing should be done with a weatherproof cualking on both inside and outside.

You don't want an SDS plus chuck, that drill is going to be mostly for drilling masonry. You could get an adapter to use regular bits with the SDS chuck but it's not what you really want.

There are drills with a regular three-jaw chuck that have a hammer setting for masonry, they aren't as good as the SDS chuck drills in masonry but more than adequate for general DIY use.

I have a Bosch that's been great, but if you like Metabo, I think these are under Impact Drills on the Metabo site:

https://www.metabo.com/com/en/machines/drilling-screwing-chiselling-stirring/impact-drills/

edit: the SBE 900 IMPULS (600865590) IMPACT DRILL actually looks super nice, it has the 43mm chuck you want, apparently its set up to be a good driver as well as drill / hammer drill - that looks pretty versatile, I wonder if there's a US version...