Is it possible to run a 1Gb SFP on an EX4500?
Yes it is! for a few 1 gig this a good solution. When you need a lot of 1 Gig putting the 4500 in VC with a 4200 (F) is another solution.
EX4500 built in ports support both 1G and 10G SFP, but rememer not for the module
Can the EX4500 also take 1Gb ethernet SFPs?
keep in mind that the EX4500 does NOT support 10/100; only 1G/10G
Yes, but it will support a 1Gb ethernet SFP, yes or no?
Yes it will.
I had my EX4500s stated for testing with 1Gb SFPs, specifically EX-SFP-1GE-T.
I had two of them joined into an LACP bundle working with a ex4200.