Tip: If you place a moon, midpoint, or dragon coin through Map16, it will always respawn whenever you reenter that sublevel. It will not respawn if you add it through the Add Objects/Extended Objects window.
I don't know if this is basic or not but I just wanted to know if there was a hex edit to make mario small every time he enters a level. I'm sure there is but I don't wanna spend an hour looking through the ROM map page. If anyone knows tell me please.
xkas is easy. Just download it and put the ROM and the patch in the same directory as it. Then, copy cmd.exe from your System32 folder (found inside the Windows folder on the C drive), and put that in the xkas folder as well. Make a backup of your ROM before this next step, just in case. Open up cmd and type "xkas patchname.asm romname.smc" without the quotation marks and with the obvious substitutions, and the patch will be applied.