As long as this isn't the one I UPLOAD to Google, can I create another build for my game using another Certificate?
you can just you wont be able to update the old version via a webserver or something else.
you can use unlimited signing certifications on google.
the certification code... or the "apk signed" includes the com.developer.mygame code that you have in all your c2 projects. if that com.developer.mygame is different. then the google system looks at it as being a totally new game... however you can still upload it over the old apk of the same game. its just tedious work doing it like that.
the apk signing or android developer certification it was used for stencyl mobile export if i recall correctly... not c2... on c2 things are much easier. depends which exporter you want to use to make an apk.
you can create that keystore with intelxdk... but it was not needed before (6-7 months ago.)
the fastest way of doing it is by using ludeis system... if you got lucky and got an account since they just launched and they where giving premium accounts. then you dont have to worry about certification and apk signing.
just to update the version of the test project..(ie. version 1.0000, version 1.0001 etc) if you use the same com.developer.mygame code everytime.
that certification is usually used .... so people cant hack your apps. as i recall... i might be wrong ... but thats what was the main reason of it .. i guess they updated their privacy now...
however for just a test on mobile just connect your usb cable to your computer and test the app via intelxdk or via wi-fi network or on localhost:yourport...
i think you can do that via browser also on mobiles directly... by accesing the preview of your project via your mobile browser. just type in your mobile browser the address that is shown on your computer browser when you preview a project.