Yes, it is working well for Twitter accounts. I would suggest you use 1 proxy on each account. You can add up to 250 accounts in 1 Jarvee instance. As for the price for 100 accounts plan, it’s around USD 80 per month for 1 PC. Contact their support to double check about the price.
Yes, Jarvee is great for Twitter accounts. It’s best to contact their support and ask about the prices regarding the plan that you are interested in. They also have a 5-days trial period to check how it works for you before you decide to pay for it.