Neither Yamaha is set up for a MC cartridge. Both are designed for MM cartridges. I doubt you will find very many, if any, home theater receivers with built-in MC phono inputs.
No one is going to be able to tell you definitively if a Yamaha receiver is going to be as trouble-free for your streaming needs as what you already have. You will have to try it and see.
The RX-A3030 does have "better" DACs than the ones in the Yamaha RX-A2030. But you are unlikely to hear any difference at all. Once a certain level of performance is achieved, you will not hear any improvement even if the one measures better. I would bet that no one could hear any difference in a properly conducted double-blind test. The Yamaha RX-A2030 has superb DACs. Companies will go ahead and put in things that measure better, because there will always be someone who imagines he can hear a difference, no matter what the truth of the matter might be. If a competitor had it and Yamaha did not, then those people would go with the other brand. This is why it is necessary for companies to put in things that are better than they need to be, that make no audible difference at all.
From looking at what the manual says (page 102), the "subwoofer trim" control seems to just be a level control for the subwoofer. Either the manual is poorly written, or it is nothing special at all.
If they have not changed it, you can read about the "ECO" mode here from a review of a previous model:
In short, do not use "ECO" mode. Read the review if you want to know more.
Oh yeah. The fifth foot on the bottom is silly. It does not hurt anything, but their claims about it are ridiculous. I still like Yamaha, but they are not unwilling to do things to sell products to silly people. Keep that in mind when considering the need for "better" DACs than are found in the RX-A2030.