✔ 最佳答案
It is possible to get bus from Singapore to Melaka, but the frequency and price won't be as good as departing from Johor Bahru (Malaysian side).
The bus from JB to Melaka should be around 2 hrs, so you could take the earliest bus and go back on the last bus. I would not suggest day trip like this. It is best to stay for at least one night.
You can walk in normally on unimportant dates, but if it is important holidays (Chinese New Year, Hari Raya......), then you must reserve, because everyone is going somewhere. If you are talking about a normal Wednesday, then I guess walk in is OK.
Do not take the train. It is extremely slow!
NB Bus station in Melaka (Melaka Sentral) is not in town centre. You need to take taxi to get to the historic town centre.