It depends. If you're not accustomed to building computers then you should definitely not get a custom built PC (unless it is pre-assembled). That doesn't mean that you should get a Mac, however. There are plenty of pre-assembled PCs that are cost effective and powerful. PCs are also better for gaming (as they have more games developed for them).
The camera built into current Macs (including the iMac, the Macbook, the Macbook Air, and the Macbook Pro) is known as the iSight
If you mean a Windows .png file then it should already have translators for it built in. If it doesn't then you can right click (Option click) on the file and chose a program from the list.
No they do not, the built in web cam came out with the MacBook and the MacBook Pro and to a lesser extent, the iMac G5.
"Custom-built" is typically hyphenated when used as an adjective before a noun, such as "custom-built furniture."
A real custom made guitar is made to your specification and hand built so in theory should be better
In online dictionaries, it is custom-built with a hyphen.
Typically, custom built motorcycles are handled by local companies that perform this work. A person should find a local chop shop that has a reputation for satisfying its customers.
Yes
low quality
Yes, the MacBook comes with a built in webcam on the top of the computer screen.
New Macs all have the same software installed. If you are referring to Garageband (See links below) then yes both the MacBook and MacBook Pro have it installed.
Yes. All current Apple portable computers (MacBook, MacBook Air, MacBook Pro) ship standard with Bluetooth built-in. Bluetooth has been a standard feature on Apple portables since at least 2005.