If serious about road cycling?

How many miles should I do a day if I would like to consider getting serious into the sport, and doing events and races,

Depends how serious you want to be!
100 miles a week is enough to get you to a good club level
If you want to be one of the quickest in your state or country then you are looking more at 20-25hrs a week which is usually around 400miles a week. When training this much it's very important to not over-train by riding at lower intensitys.

You will find that most of the pro tour riders are doing around 20,000miles a year.

Obviously natural ability and past activities/fitness levels will play apart in how fast you can become! good luck

Serious is an attitude, not necessarily a number of miles! :o)

Most "serious" riders go from 60 to 150 miles per week but it just depends on the person and on the routes they ride. There are PLENTY of very skilled, fit, dedicated cyclists....."true" cyclists.....that ride less, though, depending on time restrictions and life responsibilities and stuff.

If you want to get better and/or start racing, then you'll need to put in more miles of course....but focus on the quality of your rides, not the amount of miles.

If you have a natural talent for cycling, it will show up real
fast. Ride between 100 and 150 miles a week and try a
few local races. You'll know soon enough.

You need to get a road bike first.