Avoid Dec-Mar as it can get pretty cold and damp in the north. Since the region is mountainous mostly you can expect a bit of chilling in the evenings and mornings. At the same time because it is the mountains the weather is slightly unpredictable as well.
Accommodation should be about $7-10 a night. A meal would be $2-3 that’s about $10 a day. Coffee, refreshments or beer (assuming you’re not a heavy drinker) will cost you another $2-3. Add a daily gas budget of $3. So $25-30 a day would be a good budget. Of course, don’t forget to add the cost of renting or buying a bike. Although if you buy a bike you can sell it at the end of the trip
That is totally up to you. The north of this country is unexplored and you can spend months riding up and down the mountains. However, as I’ll show you in the post below, 3 days should be good enough for a short trip if you’re crunched for time. There are various routes or loops you can follow depending on how long you’ve got and your interests as well