Updated : 11/06/2014
NO - You cannot be expelled. However, depending on the country, you may be fined for failing to register when required.
NO – After 5 years, you are automatically entitled to permanent residence in your new country. You should not renew your registration certificate but apply for a permanent residence document, which confirms that you have the right to stay there even if you do not work or need income support.
NO - If you stay for less than 3 months each time, the only formality you might have to undertake is to report your presence, if the country requires it.
YES – You're allowed to work whether or not you have a registration certificate.
YES – If you can prove you have sufficient resources and comprehensive health insurance valid in that country, you can stay there for more than 3 months.
NO – Not straight away. The Italian authorities will initially issue you with a registration certificate. If you then stay in Italy continuously for 5 years, you will acquire the right to become a permanent resident. Once you have that right, you can no longer be required to prove you have sufficient resources to stay in Italy.
YES – Your "continuity of residence" requirement is not affected by absences of less than 12 months for serious health reasons.
NO – You still have to register as soon as possible. In Belgium, this is compulsory for all EU citizens staying for longer than 3 months. You cannot be expelled if you don't register, but you may have to pay a fine.
YES – You can apply for proof of that status from the national authorities.
NO – If you stay there for less than 3 months, you can only be asked to report your presence to the authorities – but this is usually done by the hotel where you're staying.
NO – If you stay for less than 3 months, all you might need to do is report your presence, if that country requires it.