Is this a single ticket? Like bought at once? It’s all the same terminal so pretty easy but far too tight if separate tickets imo.

Return yes, you’ll clear immigration so may take a little bit. Still 90 mins might meet MCT.

Winter might cause longer delays, and consider what flight options available if it goes wrong. I’d consider OMW as have zero faith in AC taking care of me but not sure if that’s abailabke on a share and assumes you are buying from AC and not UA?