As far as the term "paradise" in the OT, it is merely a matter of translation. The LXX uses paradeisos over 2 dozen times (Gen 2:8, 9, 10, 15, 16; 3:1, 2, 3, 8, 10, 23, 24; 13:10; Num 24:6; 2 Chron 33:20; Neh 2:8; Eccl 2:5; Cant 4:13; Isa 1:30; 51:3; Jer 29:5; Ezek 28:13; 31:8, 9; Joel 2:3).
Insofar as the NT concept of "paradise" is concerned, the majority of commentators identify it with heaven, but I found a couple of interesting comments:
On Lk 23:43--
Barnes:
It is to be remarked that Christ says nothing about the place where it should be, nor of the condition of those there, excepting that it is a place of blessedness, and that its happiness is to commence immediately after death (see also Php 1:23)...
Calvin:
We ought not to enter into curious and subtle arguments about the place of paradise. Let us rest satisfied with knowing that those who are engrafted by faith into the body of Christ are partakers of that life, and thus enjoy after death a blessed and joyful rest, until the perfect glory of the heavenly life is fully manifested by the coming of Christ.
On 2 Cor 12:4--
Gill:
Clemens Alexandrinus reads the words thus, "I knew a man in Christ caught up to the third heaven, kakeiyen eiv ton paradeison, from thence to paradise"; and so Theophilact upon the place says, "from the third heaven he was immediately called up into paradise"; and so Oecumenius, "he was caught up unto the third heaven, and so again from thence into paradise"; and some modern writers have been inclined to think there were two raptures, and the rather inasmuch as the apostle is said to be caught "up to" the one, and caught "up into" the other,
Robertson:
Some Jews (Book of the Secrets of Enoch, chapter viii) make Paradise in the third heaven. The rabbis had various ideas (two heavens, three, seven). We need not commit Paul to any "celestial gradation" (Vincent).
On Rev 2:7--
People's New Testament Notes:
Since the tree of life is found in both, Paradise and the New Jerusalem must mean the same. Paul uses the term as a synonym of the "Third Heaven," or Heaven itself (2Co 12:2-4).
I ain't gonna worry about. If I get there, then I'll know where it is.
Craig