Yes the will screw in to normal light sockets. A bulb like that will probably maintain a regular surface temperature of 120-130 degrees Fahrenheit which isn't bad by any means. It's 120 volts and most of the Y sockets we generally use are rated to handle 225 volts max. I wouldn't plug more than 2 of those into a single fixture.
I'm not totally sure, but I am not too far off from finishing my EE(more specifically Wireless Electrical) degree. But if those y-sockets are rated for 225v, then each bulb can get a max of 225v. If you are in the US then it is 120v or whatever, so each bulb is getting 120v. Now the thing that will change, is that you will be pulling more current, because in this situation, the current going to each bulb added together will equal the total current being delivered to the originating socket.
Normally, they would give you a rating of a max amperage it can handle, or maybe even max power(watts). Since, watts=(V)(I) it is also related to the current running through the socket. So that might be what you want to look at for precautions. I think I've seem pictures of people chaining them together, or are you just saying in this higher power case you wouldnt chain them together?
. The y sockets have a little embossed stamp on them that say (Max 225v.) I simply interpreted that as not being able to support more than 225v worth of lights. I can easily be mistaken, it wouldn't be the first time.
