The process and treatment varies greatly depending on where you live and even from clinic to clinic, (and can also depend on your individual situation), so the best idea is to call the clinic and ask them. A decent clinic should be willing to answer any questions you have and provide you with a consultation.
As for opinions, what exactly do you mean? Do you just mean opinions on methadone maintenance in general? I highly recommend you thoroughly research the side effects, withdrawals, and other options (detox? Suboxone?) before considering methadone, and get your info on those things from places other than the methadone clinic. Really think about how long you want to be on it and the ways in which it will impact your life. Many people end up taking it for the rest of their lives and find it unbearable to stop, and it just gets harder the longer you take it, so please keep that in mind and don't make this decision lightly

(I really wish I had not stayed on methadone as long as I have and I feel deceived by the clinic about it).
Here is some detailed info on how methadone treatment normally works in the US:
In the United States, you generally have to go to a clinic to receive methadone maintenance treatment, and there are 2 types of methadone clinics, public and private. Public clinics are cheaper to attend or free, however, there is often a waiting list due to limited funding. Private clinics are more expensive but usually have either a short waiting list or no waiting list. You will have to prove that you are dependent on opioids. Some clinics may make you undergo a series of drug tests to prove that you are in fact dependent on opioids and therefore may take a while before you can start taking methadone, while others might just make you do one test and be able to begin treatment soon after (that day or the next day). A medical examination is usually given before you start methadone, which often includes testing for diseases like HIV and Hep C. You will be asked questions to determine the level of your drug addiction/dependence and whether or not methadone is suitable for you. Some clinics will ask you whether you have tried other treatment options and only accept you if you have said that you have tried other treatment options (cold turkey, detox, etc) and failed. While there is no legal age restriction, some clinics will not consider people under 18 or will at least have stricter requirements for entry for someone who is under 18. All US methadone clinics are required to offer counseling, but whether or not attending counseling is a requirement of your treatment varies widely.
The staff usually consists of doctors who prescribe the methadone and nurses who administer the methadone (and usually will make sure you actually take it). At least when you first start methadone, you will have to go to the clinic every day to get your methadone and take it on site (often in the morning). It is normally given once a day, (unless you are determined to metabolize methadone very rapidly and require twice daily dosing, but in my experience most clinics would rather just raise your dose than give it to you twice a day and will only give twice a day dosing under unusual circumstances). You will have to submit to random drug tests. Many clinics will make you sign a contract stating that you understand their rules and agree to comply. Generally you will be started on a relatively low dose of methadone, depending on the clinic and how much heroin (or other opioid) you have been taking, and whether or not you have any health conditions, it can be between 10mg-40mg. You are then monitored to see if it relieves your withdrawal symptoms (and also make sure it isn't too much), then your dose will be gradually titrated upwards. It takes about 5-8 days for methadone to reach its highest stable levels in your system, and you may still feel some withdrawal symptoms while your dose is being raised or until the methadone has reached stable levels, but withdrawals should be minimal. Depending on the clinic (and doctor), your dose will either be raised either to a level that acceptably relieves your withdrawal symptoms, a level that is considered an effective "blocking dose" for other opioids, or some will even continue raising it as long as you say you are still getting cravings.
Also depending on the clinic and depending on your own goals from the treatment, you may have the option of either a "methadone detox", which usually lasts up to 3 weeks, a short term taper which may last a few months, or the goal may be to stay on methadone long-term or even for the rest of your life - which one of these you are doing will also effect the dose you are given. In my experience it is very common to be encouraged to stay on methadone indefinitely at private clinics. If you take any other medications may be a factor in receiving methadone treatment. Methadone is always administered orally, in the US it is normally in liquid form, mixed with flavoring and sweetener (it is sometimes also given in diskets which are added to liquid). Private clinics tend to be less strict than public clinics, but this is not necessarily a good thing.
That's all I can really think of right now, hopefully that helps and I really think that you can get a better idea of the wait times and protocols by calling the clinic, maybe call a few different ones if there are more than one in your area.