Couple of questions regarding phrasing for professional/polite inquiries

Question

My Japanese is a bit limited, as my parents are Japanese and growing up, I mostly only picked up casual conversational-level Japanese when speaking with them. Due to this, I have a severe lack of knowledge when it comes to speaking in a more polite/professional style, in particular the kind of communication that would be expected from adult salarymen communicating via email.

Would anyone be able to assist with a couple of questions? For context, I am working on creating a game as a personal hobby, and would like to request some artwork commissions from a few Japanese artists. I will be communicating mostly via email, and would like my emails to come off as polite and professional, but also as clearly coming from an individual with a hobby rather than an official business inquiry - i.e., I want to make it clear that I am speaking as a single person willing to pay for services, not as a business entity with a commercial request.

The issues I have run into that I do not have any understanding of:

1. What is generally the best first-person pronoun to use in this scenario? Growing up, I have generally used 僕 with my parents, but in a professional sense I get the feeling that this may be too immature/casual. I have generally shied away from using 私 in general, mostly because I never heard it used by my father so it feels weird to use it myself. For some reason, my gut feeling is that I should use こちら, but I do not know why I have that feeling or whether or not it is accurate. Examples of how I would use it would be:
   「こちらは急いではいませんので、数カ月待つことになっても構いません。」
   「こちらの日本語はあまり上手ではありませんので、何か不明な点があればどうぞお知らせください。」
   Would this kind of wording be okay or are there any issues with using こちら in this manner?

2. In English, whenever I have a request and want to leave open the option to decline, I generally phrase the option for refusal in the following way:
   "However, if __ is not possible, I completely understand."
   I do not know how to word this equivalently in Japanese. A direct translation of 「理解しています」does not seem like it would work, at least not via my understanding of how these words are usually used in Japanese, as I feel like 理解 tends to be used more in the sense of knowledge/understanding than in the way that it is being used in English here for acknowledgement/agreement. Is there a common phrase for this that would be equivalent to the English?

3. Is there a common ending/sign-off used in email communications that would be equivalent to the English phrase "Thank you for your time"? This is not a phrase I have ever used with my parents so I do not know what would be the common usage. I want to say something like 「お時間をいただき、ありがとうございました」but I am not sure if this would work as a general email sign-off as I kind of feel like the implication with this phrase is that we were in a meeting or spoke face-to-face.

Answer 1

I guess it may depend on the actual email, but here's an impression-answer.

Re 1: こちら should be fine. If you are unsure, use 私. It may sound strained, but should be safer at least in email. And also note you can VERY OFTEN omit subject in Japanese. こちらは急いではいませんので、数カ月待つことになっても構いません。 can be 急いでは... (with こちらは, it does sound politer; 私は here would be redundant); For こちらの日本語はあまり上手ではありませんので, it can be 私の (it's not a subject and cannot be omitted).

Re 2: I assume you mean, for the addressee to decline. I think it is implicit when you make a request, so you don't have to mention it really. But something like 対応が難しい場合はあればお知らせください = let me know if you cannot handle my request at this time may work. (side note: I'm not sure what corresponds to 対応する in English)

Re 3: My impression is, we don't generally use thanks in advance type of expressions. So ご検討よろしくお願いいたします would be a natural equivalent. I don't think this has a good English translation (literally Please take a good consideration of my request).