The speed limits in North Macedonia are 50 km/h (31 mph) in built up areas, 80 km/h (50 mph) outside built up areas, and 120 km/h (78 mph) on motorways.
In North Macedonia the motorways are numbered and prefixed with the letter A, the non motorway main roads are numbered and prefixed with the letter R, the smaller roads just have the names of the town that they lead to on the signs.
The North Macedonian motorways and the non motorway main roads that I rode on are of a good standard, the condition of the smaller roads are generally good but there is always the odd exception.
Like those in Serbia, the motorways signs have a Green background with White numbers for the motorway number, the non motorway main road signs have a Blue background with White numbers, and signs for the smaller roads have a Yellow background with Black names.
North Macedonia are not in the EU so they still have their national borders and depending on what insurance policy you have for your bike you may be required to purchase insurance for it at the border. They also do not use the Euro in North Macedonia and petrol at the time of writing was the equivalent of about 1.30 Euros per litre.
I never saw any signs for speed cameras and I never saw any patrolling police vehicles.
North Macedonia has lots of great biking roads and most of these I found in the mountainous areas of the country.
I did not buy a SIM card for a mobile phone whilst I was in North Macedonia so I have no information about how to do this.