Moy,
- For answers about visa fees see this information leaflet UK Border Agency Fees From 06 APRIL 2011
- Naturalisation or UK Citizenship is the same.
You must be aged 18 or over to apply for naturalisation. If you're under 18, you should read Can I register a person under 18 as a British citizen
- ILR is Indefinite Leave to Remain. It is still a visa with a residency restriction. You can travel to Europe with both FLR and ILR but you need to have a Schengen Visa to do so.
Look in the forum for info on Schengen Visa.