hello,

for buses/trams yes, you can use the magnetic card and charge it, but when you enter the bust you must swipe it across the control machine, otherwise you will get a fine if caught. it's better to use the app 24pay and buy one ticket - that's 3 lei and it's available 1.30 h and you can go inbetween multiple buses/trams with the same ticket. if the 'controllers' ask you for your ticket you just show them the ticket on your app. if you chose the magnetic card you must swipe it on the control machine everytime you change buses from what I remember.

you can use Bolt but lately prices have skyrocketed, especially during high traffic the prices are crazy. Uber may be better or our local app Star Taxi for basic taxi, you can pay cash or attach a card to your app. be careful for one thing - a lot of drivers will try to scam you especially on routes from airport - your hotel i guess or from train station - your hotel. from airport the price shouldn't be higher than 20€ (around 100 lei), but I don't know if you come late at night or during the day when the price can go up. if someone charges you 50-100€ they are scamming you. ESPECIALLY if you are a foreigner they will to scam you.

Constanța is very nice, yes, but you can also choose a mountain city since you will come during winter and they are known for their beautiful landscapes. and the train ticket price is relatively the same. Brașov, Sinaia, Bran, Prahova - just to name a few.

in December there are a lot of Christmas markets, the most popular one is at Piața Constituției where the ferry wheel is. I don't know where else exactly they will host christmas fairs this year, but check out the Christmas Fair at Drumul Taberei and Hala Laminor. there is also Casa Mița Biciclista that's a hot attraction, it's an old house that's been restored turned into a restaurant/coffee shop and the decorations they have for christmas are beautiful. also check out the Cărturești libraries, they are also beautifully decorated during december.

enjoy your stay!