are you limited to a maximum of 4 ship and 4 planetary leaders in Master of Orion 2 or can you hire more?

I think that is the limit, yes.

Yes, and the limit of 4 also counts the "For Hire" ones. So if you already have 4 leaders, no new leaders will appear for hire, while if you have 3 hired and 1 waiting for hire, no new ones will appear either. If an unwanted one appears for hire, and you really have no use for him, dismiss him, so the slot becomes available once more.

How do I dismiss an already hired leader?

In Leaders screen press Dismiss in the lower right and then click on the leader you want to dismiss.

Thanks, only obvious if you see it.

I've always found that mechanic really annoying - used here and in MOM of course - where a full roster means potential new hires never appear. Yes, one has the added decision of keeping a so-so leader or keeping the opportunity to hire another - but that's an absolutely artificial, contrived situation. We can dismiss leaders in these games, it's absurd that we can't dismiss one to make room for a new prospective leader at the time they appear. Other dilemmas are based on real choices one genuinely has to make, this one is entirely the result of oversimplifying the interface. In other words I think it's a bug, not a feature.

The problem is doubled in MOO2 with its two small, separate leader lists. [strikeout]I'd be thrilled if the MOO2 patching project added a "ghost" 5th position for prospective hires that could be swapped into the existing ones (as WBC3 does for the retinue and items, and MOM does for items). But I know it's not completely simple to retrofit... so instead I'll wish the past was different, and this system had never been mis-designed (IMO) in the first place.[/strikeout]

Oops, apparently 1.50 DOES have that ... I had forgotten. Cool, great! And thanks, DarzaR, for setting me straight. If you want to be doubly-helpful, please let me know how to use "strikeout" in this forum. I wouldn't want to hide my mistake, but nor do I want to leave it to mislead people.

My opinion stands - it's an annoying (and common) mechanic, and patches that fix it are very welcome.

So... you... even... dont... know... that 1.50 already have the option for unlimited amount of leaders for years, one that could be used essentially the way you describe even if player doesnt want to fully employ its benefits as a balance measure? And you just again (again) speak your usual BS about stuff you have no idea about, misleading others?

I recall that in past in other thread you already said: and the more i see what you write, honestly, the more and more you look merely as a cheap concern troll, so nothing weird in it, actually, as thats essentially what you doing.