Can do 14 days in advance or up to 7 days after the specified date.

There is no longer a 60 day multiple entry tourist visa, only single, but you could buy a reentry permit 1000b to come back in on the same visa provided total time is within the 60 days.

Years ago I "accidentally" rode (motorbike) across the Friendship bridge without getting proper stamps. Within less than a minute there were Lao cops in my side mirrors and I was "escorted" back to Immigration and put in interrogation room. Trust me, don't try to break protocol with these guys ;-)

If you arrive on Jan 22 visa free you would be stamped in until Feb 20 (the 30 days are inclusive) so leaving Feb 28 is 8 days overstay. But follow the above advice - either get a tourist visa in advance or do an extension at Immigration. Intentional overstay is bad idea ;-)

Lao visa on arrival most nationalities pay $30-35USD If you pay in baht it costs more.

Thai immigration won't let you back into Thailand without a Laos exit stamp, which means once you're on the bridge with a Thai exit stamp you must enter Laos and get a Lao visa (on arrival). Then you can turn around and go back.

The only specific policy on number of entries is VISA-EXEMPT by LAND 2 times per calendar year (by air no limit). Tourist visas no specific policy how many per year, it is at the discretion of the consular office where you apply. The Thai consulate in Vientiane has a user-friendly reputation.

To stay 3 months get another tourist visa before your May visit. You get 60 days and can extend 30 more days at immigration.

As an Aussie passport holder you can get 30 days free visa exemption when you arrive (or leave and re-enter) by air or land, extendable 1 time per entry 30 more days at any immigration office for 1900 baht, or do a relatively simple border hop for 30 more days plus again optional extension. Current restriction maximum 2x visa-exempt LAND border hops per calendar year, but by air no fixed limit. OR go to a neighbouring country (Laos, Malaysia, Cambo) and get a Tourist visa from Thai consulate, which gives a 60-day entry plus (again) optional 30-day extension. Happy New Year =)

Christmas is not a public holiday in Thailand. Immigration and other government offices will be open tomorrow.