The chorus fruit can also take you back to below bedrock, so I don't think there's any problem, unless you are stupid enough to take only one chorus fruit with you, and no obsidian and flint&steel to make a portal above the bedrock.
Of course, it's not intended to be able to go above bedrock in the nether, but this is not the only way to do it.
What I understand, the portal tries to place you 1 block to the front and 1 block under. If there's a half slab, sometimes (rarely) it places you to the bottom of the block under the half slab. See Attached screenshot 2015-02-02_22.27.08.png
Still exists in 1.8.2-pre7
Still exists in 1.8.2-pre6, offset is 1 block.
Still exists in 1.8.2-pre6
Still exists in 1.8.2-pre5, offset is 1 block.
The bug exists again in 1.8.2-pre5
I can maximize or do whatever with the window before I enter to fullscreen. After I exit from fullscreen, I cannot maximize the window, the size is fixed.
Windows 8.1 64bit, 1.6.5 Launcher, 1.8.0_25 64bit Java
What I noticed is that the placement position depends on the size of the portal. With the "traditional" 2-wide portal it places you 2 blocks to the left (in my case), but if you have a 18-wide portal (20 wide with the frame), it places you 18 blocks to the left from the left end of the portal.
Fixed in 1.13 snapshots (tested in 17w46a). LWJGL?