Plus you could get a 30 day extension if required but I'm assuming from your original post you want 37 days so just the 45 day stamp will suffice and no extension required
you can get routers which take a SIM card and there are some routers you can add a VPN to. You can try the phone as a hotspot method but not sure why you'd then need to run through a router. You could just put the VPN software on your phone and use the phone itself as a your wireless router
You can get 12 months dtac SIM with unlimited data at 30mbps (fast enough for 4k streaming) for about 1300 baht. You can pick up a 4g router for about 1000baht
If you want direct them Eva. If you prefer the journey broken a bit then Oman are very good and you can get lounge access with showers for not much money. If you've got the time maybe even do a day in Muscat on an extended layover if you can
As Garrett says, valid from day of issue. However, remember the visa can expire and you can remain in the country past that time. If you enter on the final day of the visa's life you will still get stamped in for 60 days and can extend that my another 30. The fact the visa has expired at that point means nothing, unless you wish to re-enter the country again
Credit cards/apple pay/Google pay can be used in most major shops, full service restaurants, family mart/7-11 and Lotus's. It's the smaller places and street stalls and independent places you'll want Prompt Pay and Union Pay for (plus Makro and Supercheap)