Frets? What do they do (bear with me... serious question!)

Apart from the obvious fact that they allow you to play different notes... what do frets actually do? Is it purely a personal preference or do the frets have more to do with the whole guitar feel/sound? The reason I ask is this:

I've got an epiphone acoustic guitar that I use for plunking around on. Athough the tone isn't bad, the action is terrible (particularly higher up the neck... horrid saddle!) and it has quite skinny frets on it... I think (think because I've never done it before) that it would benefit from a refret with larger (jumbo/bass frets) and the action lowering a bit... does this sound sensible?

So do the frets affect the 'tone' of you're guitar? What the chuff do they do?

On the back of this question... the saddle (and nut) on the epi appear to both be made from plastic... can I improve the sound of my guitar by replacing these (and what material would be best to replace them with?)

Thanks in advance

You know the sound of a fretless guitar/bass? They prevent that.

To the ears of a trained expert, possibly.

Take it a step at a time. Get the guitar set up properly - saddle adjusted, nut filed if needed and the usual truss rod wiggles. A fret dress may be all that you need. You're quite right in suspecting that the frets change the feel and also the sound of the instrument but most probably not to the extent that you're suspecting. Probably your best bet is to have a trustworthy tech set the instrument up with slightly thicker strings that complement the tone of the instrument a bit more. With proper adjustment, thicker strings will probably be easier to play. The fret dress itself should leave you with a silkier feel to the instrument overall. My local would take about £90 off you for the entire job and really make that instrument sing.

Yeah, but I think the air freight would be prohibitive.

I think that it's about 40 Euros round trip - the transport risk is one I'd avoid though. cb PS Been to ulis yet?

Nope, I'm trying to avoid guitar shops atm.

Thanks for the advice folks... so is it purely down to personal preference when it comes to frets then... I'll go with a decent set up first as advised and take it from there.