Three major issues here.
The first is that you don't seem to be aware that you're effectively building a dimmer circuit when you start using electronic switching. If you Google "theatre light dimmer schematic" you'll find a few useful links, including an old ePanorama article about different types. You may find useful links on the Everyday Practical Electronics site too. This is almost historical now, since it was basically invented in the 1980s and couldn't be done any better/differently.
The second major issue is that you aren't aware that your design is badly flawed. Regular domestic 60W bulbs aren't designed for decent stage illumination. The throw is all wrong, and besides they simply aren't bright enough to do sod all. Stage lighting needs crazy amounts of power if you're using incandescent lights. When you use that kind of power though, you get a lot of heat, and then you need the design of a stage par to keep that under control. So you might as well buy stage pars.
Except that all that power is a nightmare to manage. It's a real job to make sure you aren't going to blow fuses during your gig. And worse, your switching circuit is going to have to dissipate high levels of heat too. As well as having to not interfere with the sound when it switches on and off, which is a perpetual problem for every mains dimmer ever made, even the best ones. Actually, never mind your sound - you also need to not block TV and radio reception for a couple of blocks around you.
The solution which every stage and every gigging DJ and musician uses these days is LED pars. Fairly cheap, low power, decent brightness, controllable over DMX. Job done.
So if you're going to build your own lights these days, you should be using LEDs. Do the job properly. Of course it'll cost you much more to make it yourself than to buy it off the shelf, but then you were going to have the same situation with your original suggestion, so I'm assuming you're doing it as a project to learn electronics, and not because the end result will be very useful or cost-effective.
There's a third problem too, though. This involves mains voltage, and you very clearly are not yet highly skilled at electronics. This presents a clear hazard to you, your house, and everyone living in your house. I strongly advise you not to attempt this, because you don't know enough yet to be safe with mains.
Edit to add: If you're planning on gigging as a DJ, this also presents a clear hazard to everyone at your gigs too. Your homebrew kit will not pass an electrical safety test. If anything goes wrong then you are directly to blame for gross negligence, and your insurance will not cover you. This means you and your family could also lose your house and every possession you have.
If I've not made it clear enough, you really shouldn't be doing this...