A: No, doing so will result in an error when running UberASM Tool. First, you need to remove the original patch: either try to use the Unpatcher tool (at your own risk) or port your hack over to a new ROM.
A: Yes. If you want to disable infinite lives, you can use the !infinite_lives global setting (see Global Settings - Quality of Life Settings). If you want to keep infinite lives just for specific levels, you can do so using the %no_lose_lives local setting (see Local Settings - %no_lose_lives).
A: Yes. Look at the Local Settings - %checkpoint page.
A: Yes. Look at the Local Settings - %retry page.
A: You can do so with the !death_sfx option in settings_global.asm (see Global Settings - SFX for details). You can also find a custom death sfx file that replicates the vanilla death music intro under amk_resources/sfx (see AddmusicK Resources for details).
A: Yes. Additionally to the effect table, there's the !ram_prompt_override address that, when set, will replace both the table and the default option (see retry_config/ram.asm and RAM Map).
For example, you could use it to let the player choose the prompt type as they want (you still have to implement that, though, as this only handles setting the prompt type).
Note that this address by default is never reset outside of title screen load.
A: Yes. Look at !no_prompt_box in retry_config/settings_global.asm. You can also remove it only under certain circumstances by setting !ram_disable_box to 1 (for more info, see retry_config/ram.asm and RAM Map). For example, you can do it in a Level ASM init to make a level not have the option.
Note that this address by default is never reset outside of title screen load.
A: Yes. Look at !no_exit_option in retry_config/settings_global.asm. You can also remove it only under certain circumstances by setting !ram_disable_exit to 1 (for more info, see retry_config/ram.asm and RAM Map). For example, you can do it in a Level ASM init to make a level not have the option.
Note that this address by default is never reset outside of title screen load.
A: Yes. Look at !text_x_pos and !text_y_pos in retry_config/settings_global.asm. For example, using !text_x_pos = $08 and !text_y_pos = $D0 will place it on the lower left corner of the screen.
Additionally, you can also change it at runtime by writing to the !ram_prompt_x_pos and !ram_prompt_y_pos addresses (see RAM Map for more info).
Either way, if you want to change it you should disable the Retry box (either by setting !no_prompt_box = 1 or by writing to !ram_disable_box at runtime) as its position can't be changed easily.