Heating and lighting question

[Wendy]

Hi,
I've posted this in the tree frog section but had no replies so I thought i'd try here.

Ive had my three Australian tree frogs since October and this is my first winter with them. The bulb has gone and need to replace it but wanted to check before I got another one that I have the right ones. I have TWO repti glo 2.0 UVB lamps in a double canopy over an Exo Terra 60x45x45cm (24x18x18 inch) terrarium. Is this the right strength and type?

Also do I need any separate heating now its winter.

Temps 70-75 (gets colder at night)
Humidity 70%
They eat crickets (dusted)and occasional meal worms. But I feed them by letting the crickets into the terrarium so find it hard to see who is eating what. I've been thinking of doing it a different way, any thoughts. They have always slept behind the water fountain or under the plants during the day and are active at night. Just recently though I've noticed they aren't as active, is this something that happens as it gets to winter or should I be worried.

Any help would be greatly appreciated as I want to go and get the new bulb asap.
Thanks.