thanks for the suggestion, it's an option. However, as the price of Laotian E-Visa and Thai immigration fee are the same, I save myself 1 trip to the border if I do it like outlined. And also, the number of border bounces are limited to 2 or 3 per year, so I'd keep that ace up my sleeve for later.
Technically possible and not illegal. However, if an immi officer flags abuse, you might be refused entry. Also, keep monitoring if the 45day program will indeed be available as needed.
Depends. Basically CNX offers the option of passing through customs and immigration there even your first touch down is BKK. IF you are on a properly routed (code share) connecting flight. Then your bags are being taken care of and routed through. No more than 1.5 hours connecting time necessary.
If this doesn't apply, I suggest 4 hours buffer minimum.