[Budget]
~5000+

[Purpose]
- Gaming, media streaming. Centre monitor for game, side monitor(s) for browsing/youtube/walkthroughs.
- Will upgrade to triple monitor setup later.

[Hardwares that will be re-use]
- BenQ RL2455HM as a side monitor, Thrustmaster wheel.

[Monitor resolution]
- 1080p

[Games & softwares that use frequently]
- Planning to play DiRT Rally, Euro Truck Simulator, MGS V, strategy/sim games (Civ/AOE/Sim City/Football Manager/etc), Witcher 3. No AAA games later than 2015 (except Witcher 3).
- Dolphin emulator
- PC will become server to stream movies/music to nearby devices. Going to use Kodi, Plex, Spotify
- Exact Audio Copy

[Personal preferences]
- Not interested in overclocking (yet).
- Old games (2015 and earlier) at highest graphic settings. Hopefully can play Witcher 3 in a decent graphic setting possible without using overpriced GPU. As I'm just catching up playing older PC games, maybe I won't need a powerful GPU yet I guess.
- Not sure if triple monitor gaming will still require the overpriced GPUs. If it does, I'll use one main monitor for gaming and one side monitor for walkthroughs first and upgrade later.
- Bluray drive to watch movies and rip music CDs.
- SSD for boot, large storage for media
- will connect the PC to an AV receiver for 5.1 sound.

[Location]
-Perak

Please suggest a build for me (with an okay-ish GPU, maybe for use with 1 or 2 monitors first), with ability to expand to a triple monitor setup with more powerful GPU later (different budget) once GPU price goes down.

Thanks for your suggestion.
If I want to go for triple monitor setup later, do I just have to change the GPU only and add the monitors needed?
Do I need two GPUs or just one is enough?