I tried many of the games on a model 1 front loader and every game flips out and you cant play. Yes all Top Loaders are the same. (unless it was modded.)
Little Red Hood & Duck Maze do work on a front loader. These are non licensed games and they don't have any issues.
I personally don't own a Modded front loader, but I think it plays everything a Top Loader does.
PAL A & B are just different region frequencies, US and Japan are NTSC, PAL B is most of Europe and PAL A is mainly Australia & South America. There's also SECAM but I've honestly haven't seen much games offered as SECAM, This is mostly Russia & Africa.
If you bought a PAL NES and tried hooking it up to a NTSC TV you wont get anything on the screen. Some HDTV's can read PAL.
The other part that's a problem is the voltage difference, To use my PAL consoles I have to plug them into a volt converter. And while you can plug a Japanese system into a US outlet it's technically not good on it. I use a volt converter on my JP consoles as well. US has a higher voltage then Japan does, and this can fry out your JP console over time.
There's a lot of games you can find that may have you think its a PAL exclusive but its just been renamed overseas. Like Yoshi in the US is called Mario & Yoshi in EU.
Heres a list of games released in PAL but never in the US. Many of these have been released in Japan.
Aladdin
Asterix
Aussie Rules Footy
Banana Prince
Beauty and the Beast
Championship Rally
Corvette ZR-1 Challenge
Crackout
Devil World
Dragonball
Dropzone
Duck Maze
Elite
Four Players Tennis
Hammerin' Harry
International Cricket
Jackpot
Kick Off
Konami Hyper Soccer
Legend of Prince Valiant
Les Chevaliers Du Zodiaque
Lion King
Little Red Hood
Mr. Gimmick
New Ghostbusters 2
Noahs Ark
Over Horizon
Parasol Stars
Parodius
Rackets & Rivals
Road Fighter
Rodland
Smurfs
Super Tarrican
Trolls in Crazyland
Ufouria
And yes New Ghostbusters 2 is one of the games I highly recommend playing. The Ghostbuster games we got where garbage compared to New Ghostbusters 2.
I Hope I was able to answer everyones questions.