Paul,
Just a few tips which may be difficult to find through Help:
Type:
When you wish to change the general size of Type (text), make sure you select the whole Type Object; you may do that with the (Direct) Selection Tool (one of the arrows).
When you wish to change the size of specific characters/parts of Type, make sure you select (only) the relevant part with the Type Tool (the T).
If you do the opposite, you will regret it.
Stroke Weight:
That is what you called line thickness in the OP. It is in the Stroke palette/panel.
Both:
You can use the dropdown and select values, or insert; both have pt for points as default, but you can use other units by adding their abbreviation (mm for mm, cm for cm, in for inches, px for pixel (which is basically the same as pt), and you do not want to know about picas.
If you must, or wish, you can also change units generally, Edit>Preferences>Units & Undo; any change persists until changed again, across documents.