Peter – maybe some slight help in lieu of a real expert turning up:
1. There were a number of Grenadier formations during the war, but I'm not sure which ones you mean.
a. Permanent Grenadier Battalions – Provincial Militia Regiments of 2 battalions each from Andalusia, Galicia, New Castile and Old Castile.
b. Ad hoc Grenadier Battalions – converged Grenadiers, same principle as equivalent British and French formations.
c. Newly-raised Grenadier units. Unfortunately I know of no source which suggests in what sense they were 'Grenadiers'. A couple of them appear to have been called 'of the General' or 'of the Army' which might suggest that they were converged Grenadier Battalions as above. Others ('de la Canarias' and 'Fernando VII) just seem like fancy names. I don't know of any large-scale re-organization taking place. Do you know when exactly this was mooted?
2. By civilian contractors until 1813, except for the horse artillery batteries.
3. There is a decent page of plates in this one: link
Regards