maneki wrote:1. Is it okay to burn candles as pastime (even when not casting a spell), or is it too sacred?
Feel free to use candles how you wish. Religious practices don't have a monopoly on their use.
maneki wrote:2. What are considered offerings/how do they work?
If you don't know what a specific being (deity or otherwise) wants, just ask Them. Some will ask for food and beverages. Sometimes if you're asking Them for something in particular, They will ask for something similar in return. I don't think any benevolent being will ask you to give Them things that you can't easily obtain. You don't even have to make physical offerings. Virtual offerings work just as well.
maneki wrote:3. About how much knowledge do you need to be able to write your own spells, and how long does it take? How do you know that they will work and not be too vague?
I think this depends on the individual. You can easily write spells with little knowledge. I suggest first just altering the spells you find in books or online. Little changes would work, like changing a different candle color, using a different crystal or invoking a different deity. Once you've got the knowledge of how spells work and the experience of casting them, then you can work toward writing your own from scratch.
For some spells, you do have to be as specific as possible. Magick takes the path of least resistance. Despite our best intentions, spells can occasionally take unexpected form. For example, maybe you perform a spell to have more time to spend with your family. To you this might mean being able to get a job with a shorter commute between work and home. The universe might instead see to it that you break your leg and have to miss work for a period of time. Well, you're at home more now.
Sometimes, we don't know how well a spell is going to work until we try it. If it works, great, we know what to do next time. If it fails, great, we know what to change next time.
maneki wrote:4. When are wands necessary? Are they necessary?
Wands are a way to direct energy. You can easily substitute it with your athame, your finger or anything you wish to point with.
It is used to cast circles and to stir energy and even physical things like potions in our cauldrons. Personally, I don't find them necessary. I have two, but I don't use them.
maneki wrote:5. Do some spells take longer than other spells? Are any able to take effect instantly?
I agree with Adastra's response. It depends on the spell. If a spell is long term, it may need to be "refreshed" from time to time. If you perform a spell on an object, the spell will have to be done again if you replace the object. A car or a house would be good examples. Some spells are set for a specific amount of time. For example, let's say you had to deliver a pizza to a bad side of town. You could set up a protective shield around yourself that would be active just while you're on that side of town. If you're only going to be on that side of town once, you would only need that spell once. If you find yourself going to that side of town often, you'll want to make sure that you have a spell that will activate every time you go to that side of town.
