The speed limits in Panama are 40 km/h (25 mph) in built up areas, 60 km/h (37 mph) outside built up areas, 80 km/h (50 mph) on dual carriageways and 100 km/h (62 mph) on certain sections of dual carriageways and Toll motorways.
In Panama there are only 3 Toll motorways. They are all in and around Panama city. The first 2 are the South Corridor and the North Corridor which form a ring road around Panama city. The 3rd is a road that joins the North Corridor road and goes to city of Colon at the Caribbean end of the Panama canal and this is also a toll road.
To use these roads you must first register your vehicle with the company that operates the toll roads and obtain an electronic pass that is affixed to your bike, there is no way to pay with cash as the toll booths are unmanned and fully automatic. I did not do this but if you are considering this the following website is a good English language guide to the process.
https://www.residepanama.com/en/reside-panama-blog/how-to-obtain-your-panapass-in-panama
All of the road signs for the main roads are Green with White writing. The Toll motorways are indicated on theses Green and White signs with a Blue box and with motorway symbol in White inside the Blue box. The local road signs are White with Black writing.
The Panamanian Toll roads I can not comment about as I was never on them. The main Panamanian roads are Highway 1 and Highway 2. These are generally good however, Highway 1 tends to get worse the closer you get to Panama city. The condition of the smaller roads are generally poor, degrading to pothole ridden obstacle courses in sections.
I would not recommend riding anywhere in Panama at night due to the number of very large potholes that are on the roads.
Petrol at the time of writing was about 0.95 US Dollars per litre.
Panama is awash with police using hand held speed guns and they are everywhere. On most roads where the speed limit changes you will find a police bike parked up in the shade or under a bridge operating a speed trap. Sometimes the speed limit signs are obvious but sometimes they are not.
There are also a lack of signs on exiting built up areas telling you that you have left it so you can be riding for a few miles before you see a sign telling you that the speed restriction is over. Such signs are either the higher or lower speed limit signs, or a Yellow diamond shaped sign wth Black writing telling you (in Spanish) to reduce or resume your speed. All very haphazard so beware.
To buy a SIM card for a mobile phone you need to go to any mobile phone retail shop and you are required to produce your passport to buy the SIM card. When I did this the cost was around 5 US Dollars for 7 days of unlimited internet.
However, I have spoken to other travellers who told me that they were not asked for their passport when buying a SIM card. Like most things in Panama, the rules can vary depending on who your are dealing with at the time.