hi WharfRat & administrollaattori ~ thank you both very much for all that percise info, i sincerely appreciate it
because both methods were bit beyond my scope of understanding regarding Terminal commands etc... . i ended up sticking with the simplistic method i have used in the past with Mint of simply making a copy of the .mozzila hidden folder ( that resides in Mint's Home folder ) and moving that ( along with all my other standard non-hidden Home Folder contents such as Desktop , Pictures , Documents etc , as one can only move the contents
of a Home Folder because the Home Folder itself will not allow itself to moved as a complete stand-alone folder onto an external hard drive ) to an external 500gb USB 3.0 Hard Drive ( that i prepared beforehand by formatting this external Hard Drive in ext4 with the GParted utility ) , and then simply migrating / moving it all onto my new computer with drag and drop off the external hard drive. it worked out fine ( im typing this from the new computer now ) , and this method maintained all my data ( approx. 80gb or so ) ....and once i replaced the default .mozilla folder with my old one ( in the new computer's Home Folder , must allow hidden folders in " view "to see it , then deleting the default .mozilla folder and replacing with the .mozilla folder that i moved over on external HD ) , all was perfect and as it was exactly on my old computer ... all ad-ons / extentions / themes / bookmarks & passwords carried over to the new version Firefox ( version 24 ) and worked perfectly.
on a side note , i actually tried to use a Firefox add-on called FEBE that claims to make a perfect Firefox profile backup ( and could supposedly restore it easily ) , but it was dreadful and did not work at all ( very buggy ) , and i do NOT recommend this FEBE add-on to anyone. however , if one is migrating from one computer to another as i did , and both the old and new computer have an active online connection , there is always the option to simply use Firefox Sync ( in the tools menu in Firefox ) , as that will , from what i have read ( https://support.mozilla.org/en-US/kb/firefox-sync-take-your-bookmarks-and-tabs-with-you
), sync all one's Firefox data ( everything including profile / add-ons / extensions / passwords ) from the home computer onto another computer ( or device like a tablet etc ) that has Firefox installed on it. one must first set up Firefox Sync on the home or base computer to use this " Sync " method. just thought it was worth passing that info along for anyone who may need it. once again , thank you both for all of your kind help , tips & advice. all the best to you both !
Mint 15 Cin 64bit(Tux3.8)FF25
Lenovo y580 i7 3rdGen Intel QdCore i7 2.4ghz 6MB Cache16gb RAM
Intel 520 mSata 240gb SSD main
Samsung 840 SSD 512gb 2nd internal
Nvidia GeForce GTX660M / Intel HD Graphics 4000