How are weights and currencies dealt with if a site uses a different culture than my account? Does Pressero do any weight or currency conversion?
Pressero does not convert weights or currencies.
Your account's main culture is configured when your account is provisioned and cannot be changed (except through the database, by our programmers). Site cultures can be set in Site > Settings > General Info > Site Basics. If the site culture for one of your sites is different than the culture of your Pressero account, then the weight/currency of pricing engines and shipping methods will be interpreted to be in that site's culture.
Example
Your subscriber account was configured as English (US).
Site A is also set to use English (US) culture.
Site B overrides the main culture setting and is configured to use English (Canada) as its culture.
You have a shipping method (configured in Preferences > Shipping) with a maximum weight per package of 10.
On Site A (US culture), that shipping method has a maximum weight per package of 10 lb.
On Site B (Canada culture), that shipping method has a maximum weight per package of 10 kg.
You have a pricing engine where one item has a cost of 50 and a weight of 5.
On Site A (US culture), that item costs 50 US dollars and has a weight of 5 lb.
On Site B (Canada culture), that item costs 50 Canadian dollars and has a weight of 5 kg.
If you need your shipping methods and pricing engines to take into account the difference in currency value and weight units, you should create separate shipping methods and pricing engines for your separate cultures.