You want to have one day on and then one day off. The muscle needs time to reknit and repair. You'll see much more visible results this way and won't risk straining your arms. Just destroy it on day "A" and make sure to eat right throughout.
I think you would be better off every other day. you need to rest your muscles in between work outs, or you could pull something, or injure yourself. Don't over do it.
I would suggest doing push ups every other day. This gives your muscles enough time to recover and build strength. In total I suggest doing 20-30 push ups every other day.
Yes. If you are looking to obtain strength in your legs and especially your arms it's a good idea. Doing a few push ups daily is a good routine to get into. In no time you should have wonderful upper arm strength and you will have very toned arms.
i agree with everyone u should rest 1 day and train 1day but do a minimum of 100 pushups in different variations and max reps cause u wanna push your limits 4 results such as mass,cuts etc and obviously strenght