Estimate of travel expenses for a Colloquium abroad - what does this include?
Tickets and accommodation are typically by far the largest items.  You can also include other transportation expenses, such as travel to/from airports (or parking fees if you drive your own car to the airport and leave it there).  You should generally choose the cheapest option that's not too inconvenient.  For example, an airport shuttle may cost much less than a taxi.

Meals can be handled in many different ways: sometimes there is a fixed per diem amount to cover such expenses, sometimes you can be reimbursed but need receipts, and sometimes meals aren't covered.  The per diem approach is generally easiest for everyone, but it depends on how much funding there is and where it came from.

Other forms of travel expenses are less common and may or may not be covered, but it can't hurt to ask.  Childcare is a particularly messy issue, because this can severely limit travel plans but conference organizers are not necessarily prepared to provide funding or local recommendations; still, it's worth asking about childcare if it's relevant.