Except the people in Malaysia are really awful. Thais have their moments but Malaysians are infinitely worse. I don't like travelling to Malaysia for this reason, even if the visa process is stupidly easy. Also brings a lot of foreign trash which also really spoils the vibe. I've seen people stab others in the eyes with knives in hostels and rape drunk foreigners etc. No thanks.
best to always check your stamp. Immigration officers often stamp the wrong dates and you need to clear it up at the immigration where the mistake was made. So best to check before you leave. Always. The onus is on you every single time.
depends on the agent and their agreement with land border immigration. Things are changing daily, but about 6m ago I saw overstays being cleared at the Malaysian border via an agent...