4ftx2ftx2ft ~ 120cm x 60cm x 60cm /1000 = 432L. Of water.
For 4ftx1.54ftx1.5ft ~ 120cm x 45cm x 45cm /1000
= 243L .
This assume you fill the water till the top tip and no substrate and deco (blank Tank).
Yes. It is recommend your filter to have 6X FLOW cycle of your total tank water volume.

to be honest, i was quite surprised at the tank volume for the same 4ft but 0.5ft extra... wow... i shld've got the 4x2x2 one! hahaha...

Ehiem is good enough, buy 2217 not enough power. For my 4x2x2 I use 1-1028, 1-2026

kevin, it will be just nice actually. but to be honest, the price u r going to pay for the eheim might be a little high. last i recall is about rm1500 for the unit. but it depends on how deep your pockets are in comparison, the taiyo china filters i'm using are about rm120-150 each.... of course the media cannot beat eheim la...

i believe most aquarist here are using at least 2 filters on their 4ft tanks.  you can then put the filter on either side. or one on each side. this is to make sure the water movement is equal everywhere in the tank.

to keep thing simple just run double eheim 2217...i think its cheaper than 1500xl
plus with two filters, u can clean it one at a time

rm459 for eheim 2217 with free full media? if not then not cheap. go pasar pudu Alive aquarium, last time i got it for rm450 with free full media.
even at rm499 with full filter media is better then rm459 with sponge only. Those media along worth >rm200 if purchase separately , else those sponge outside LFS selling for RM10 each only(those they taken out from eheim 2217 when they setup for client).