1. Depends on your workload and how well you manage your time, but for a busy Year 12, 20-30 minutes a day or every two days won't hurt, although if you do a practice exam that's a two hour commitment which you might wanna reserve for the weekends.Questions...
How much time per week should I practice on UCAT questions?
Should I be mindful when choosing test locations and dates?
Is the screen calculator useful?
A close friend of mine failed to secure a place this year so I think I should investigate this thoroughly.
2. If there are multiple testing locations available, choose either the closest one to your house or the one which you will experience the least traffic jams getting there. I specifically avoided the one in the city for this very reason. As for time of day, I recommend doing it in the morning where you're the most alert and awake but not too early that you might have trouble making it on time. 9-10 AM is good.
3. Yes, some questions such as calculating the percentage x is of y or the volume of a solid can be done much faster on a calculator than in your head. Don't be overly reliant on it though, and always run the numbers it returns through your head to check if it makes sense and you didn't type something wrong.