Train from Florence to Monterosso Cinque Terre

Will the hotel I am staying in Florence assist with purchasing train tickets

You need to ask them

How long is the train ride from Florence to Monterosso Cinque Terre

2.5 - 3+ hrs depending on the departure you choose. You will have to make at least one change.
This will give you some info--

https://www.bahn.com/en/view/index.shtml

There are many trains during the day, all requiring at least 1 connection, and most 2 connections. Takes anywhere from 2 1/2 to 3 1/2 hours. The closest thing to an express train is a Frecciabianca to La Spezia at 7:28 in the morning but it goes only from Firenze Campo di Marte station on the other side of town, not the main station, Firenze Santa Maria Novella.

You can just go to the station and tell them to get you on the next connection to Monterosso. If it is all regional trains, it will cost 17.60 EUR pp, a few connections may involve fast trains for one leg and they will cost up to 31 EUR pp in the case of that Frecciabianca from CdM.

mary,

You can check all the train solutions from Florence to Monterosso on the Trenitalia website. Your departure station will most likely be Firenze S.M. Novella and your arrival station Monterosso. Some of the trains you'll be using will undoubtedly be Regionale and if using locally purchased tickets for those, you MUST validate them prior to boarding the train on the day of travel or risk hefty fines, which will be collected on the spot. In most cases, there will be one or two changes on that trip (Pisa Centrale, La Spezia Centrale?).

There is a departure at 09:53 with just one change at La Spezia Centrale, and a travel time of 2H:54M. Both of the trains on that departure are Regionale. There's another departure at 10:28 with a travel time of 2H:25M and one change at Pisa Centrale.

It's doubtful that the hotel will assist with tickets, but they might. Buying tickets is very easy using the automated Kiosks or you can use the staffed ticket office if you wish. I often buy tickets the day prior to travel so I don't have to bother with that when I'm hauling luggage. You could do that but DO NOT validate the tickets until just before you use them!

Good information above but just to add, you're likely going onward from Monterosso (or back to Florence?) at some point so would need tickets for that journey as well?

I doubt very much a hotel is going to "help" with tickets unless it's maybe a posh, 5-star with extensive concierge services, and you'd still need to understand what sort you have and how to use them so back to all that good info posted above! :O)

mary,

One other point to mention. For your ongoing journey from Monterosso, there's a full service ticket office in the Monterosso station, and I've found that the agents there speak some English so it's an easy place to buy tickets. Again, if you're using Regionale trains be sure to validate these prior to boarding the train on the day of travel. As I recall, there are validating machines both on the platform and in the sottopassagio (tunnels) in the Monterosso station.