1: I do do this on daily basis. ('do' suggests a firm habit, determination, fixation to something)

2: May I come in? You do come in. ('do' acts as an intensifier)
3: I will do it.
4: I would do it.
5: I do will/would do it.

Is '5' grammatically correct? When 'will' is used, it in itself carries the notion of determination etc. If there is slack in determination then I would go with '4'. Therefore, use of 'do' in '5' doesn't add to any effect. What do you have to say on this? Please let me know.

Best wishes
1-4 are fine but 5 is incorrect.
Thanks, Phillips.

Do you find my reasoning plausible? Please let me know.