[Always *]

Like Dez, I'm not trans, but I know many trans people and feel like I can shed some light on the topic for you

1) Pronouns and names
I find it is best to ask the person. It might feel weird, but they'll either tell you themselves, or you can simply ask. I have done this before and they're totally ok with it. Something as simple as "do you want me to use female, male or "they" pronouns when I talk to you or about you?" can go along way. I think it shows respect by asking them if you are unsure, instead of just assuming and incorrectly labeling what they choose. In terms of name, that might depend; your friend will likely want to think about a name he (she?) has the best connection with in with the gender of her (his?) choosing, again, you can just ask, but he (she?) will probably "come out" with a new name when she (he?) is ready.

2) Age
I know many people who "came out" as trans when they were quite young (like 10-13) and possibly identified even sooner. I know other people who always sort of knew, identified or felt differently in their own minds for a long time, but never "came out" until they were in their 20's (or older)

3) Supportiveness

As I am not trans, I cannot speak to this personally. The reality is that trans people have more trouble accessing quality health care, particularly in countries like the USA where people are more conservatively minded, they are often bullied more, face higher murder rates and homelessness and unemployment rates. That said, that is not the experience of everyone; I know many trans people who have supportive friends, families, employers, and their lives have not been adversely affected by their choice (although I cannot guarantee what people not close to them have said).

4) Biggest struggle in transition process

I'm not sure if I will be right here, but I think there will be a few struggles. One will be acceptance from those in the trans persons life. As much as it is his/her own choice to transition and no one else has to accept that, it does suck when people reject you or are cruel, especially those who were previous close to that person. A second one will be the physical process of the transition; the hormones can be expensive, and the surgeries such as getting or removing boobs (can't remember the proper name, sorry) can be painful. A third challenge can be the body dismorphia that a lot of transpeople have to deal with; it can be hard to look at yourself without any clothes on if you're still living in the wrong body or haven't fully transitioned. The body dysmorphia can be very psychologically trying and I think could probably cause anxiety or depression from what I've heard. There are probably many other things, but those are just a few I can think of. It'll affect everyone differently though.

I skipped the 5th question because it wasn't really one I could think of an answer to as it relates a lot to personal experience.