Configure Exchange 2016 + DNS (MX from our webpage mail to flow to our exchange)

We need to configure some things in windows server 2016, the job is as it follows: -We need to configure Remote acces to the server (by now the only way to acces is via OVPN to our router and from the intranet, access the server via remote desktop, from there you can also connect to the pcs that need to be configured to the exhange from the outlook 2016) -We need to configure the DNS properly to point the MX dns of the external domain to point at our domain, not a hard job. -We need to configure Microsoft exchange 2016 to get the email from outside domain, and be sent trough that same domain (the active directory is configured with the same .com domain of the internet server) -Configure and test 2 of the users, the directory will have arround 12 users, but the most important will be 2, (the other we will add them later as we will need to be able to manage all the users in the future by ourselves) wich will need to be tested and shown to us that is working, for: ..Email sending / email recieving (from intranet and out world) ..task organizing synchronizing properly ..calendar synchronizing properly ..Be able to have outlook in our mobile phone, away from the office, and have the outlook ..synchronizing the tasks and calendar and mail properly (this is quite important for us) -We also want to review the basics of security of our server, for preventing external intrusions what we have now: Microsoft windows server 2016, phisical server, 32gb ram, , in a dell t330. in there we have the active directory, setted up, dns server, hyper V. in Hyper V we have a virtualized windows 2016, with the microsoft exchange with mailbox role. the microsoft exchange is able to contact the active directory correctly, and resolves the internal dns form any of the computers in our site. what we have and what we want adn why we change: Actually We are using a website domain .com bought to a 3rd party where we have the mail server, and a webpage hosted, the mail server is sending to our exchange via pop3. but we ant to migrate to the exchange in our own server for having the ability to have a calendar and task organizer. and also file server in a future. drawbacks that are going to be solved early: We still do not have a FIX PUBLIC IP ADRESS, we are working on it i can imagine that in a couple of days we will be achieving that. NOTES we will appreciate a good level of communication, so we can have a future contact with you, for when we have a problem we can hire you again, and will be needed to train us a little in a dayly managing of the server, as we come from a linux server, we are new on W.S. 2016. have in mind that the first connection will be trough OVPN and from there you are in the network for aonnecting to remote desktop of our server, i think until we have the fix public ip or you configure the remote connection properly we will be like this. the server connects to a switch where all computers are connected, and acces the internet trough the Router asus RT-AC68U, wich has the OVPN function, an will be needed to configure for remote connection i think. thanks