Just wondering should this sentence be: "Ólfaimid an fíon anocht." Because does tonight not imply that it is the future?
Like in English, Italian and other Indo-European languages, the present tense can be used to express something that's planned in the future.
Yes, as scilling said this is mostly not the case in Irish. Post my comment below, I did a sample read of three novels and didn't find a single instance of the present being used for the logical future.
Yes it should be. Irish uses the future tense for almost all future events, the most common exception being with "Má" clauses.
Má ólaimíd an fíon anocht, ní bheidh aon fíon againn amáireach.
(Note: I am intentionally not leniting "f" in "fíon" as it is common to leave "f" unmodified after "aon" in native speech for comprehension.