VoiP takes very little bandwidth, so any internet connection, be it via a SIM card, which is what I presume you mean by 4G Dongle, or via 1Gb/s optic, should be OK for phone calls.
If you do the monthly transfer of 65k, then every satang can be spent on whatever you want.
My IO accepts the Combination of Bht 40,000 per month = Bht 480k per year, plus Bht 320 in the bank, totalling Bht 800k per year.
Sod the pop-up ads, get rid of that ridiculous yellow invitation to subscribe to Asean's email, sometimes with the Captcha to pick bicycles, bridges or lorries.
I still get it even though I HAVE subscribed.
He mentioned TV in his OP, which I do not think that 50Mb/s coming in, and then being sent out via WiFI will suffice. I could be wrong but in my experience, no.
I never had any problems with Wise transfers being accepted by IO, as long as it shows the money came from outside Thailand, so click the Long Stay reason when doing it. That takes an extra day to transfer so do it the day before you need the dosh.
The keyboard language can be changed in your settings.
My Thai phone works perfectly in UK, or Dubai, so why not vice versa.
My Huawei Y9 2018 is used daily and is as efficient as the day I bought it.