This is a little more then a 5 pointer project... There is so many questions and concerns you need to prepare before hand. I'm assuming it is not coming from an existing domain/setup so I'll just focus on a new domain setup.
1) do I need to buy 30 CALS for server roles...and another 30 CALS for exchange as well????
Depends on how he is going to function the application server as. Is is going to be a terminal server\application server? Are users remoting into it to use an application or it is simply hosting an application that they will access from a network share or directly installed on their desktops?
If they are going to remote into the server and use it as a terminal server with the application. You will need 1 CAL per user remoting in. If not and they are going with the second option. Then no CALs for this server is required and also Terminal Services role installed with Terminal Services licensing activated.
As for Exchange. They changed the licensing since 2013 onward. You now need 1 server CAL per user and 1 Exchange CAL per user (also if they go with Enterprise edition of Exchange 2013/2016, that is an additional CAL license). So again, depending on the product you are using, you may need 60-90 CAL licenses.
2) What does he means he wants two different server one Domain controller and other application server.
As he states. He would like a domain controller (which normally hosts roles such as Active Directory, DNS, DHCP etc... to manage the infrastructure) and an Application server (with or without application roles depending on his needs) for application usage.
This normally has at minimally, Active Directory and DNS roles installed. Today's standards you will want DHCP role on their as well and take DHCP off from your router. This is the first server you will want to configure. However, there are a lot of things to consider when making a new DC. Such as:
What Domain Name will be used?
Has the client already purchased the domain name or will you be using a .local type domain?? (which is not advised as you can not purchase SSL security certs for .local domains anymore and you will most likely want/need a cert for Exchange) this is where split horizon DNS comes into play. I would advise he obtains a domain name such as a .com and uses that from the start.
Storage & Raid Type
Does the servers have enough storage to handle the roles plus up to 3 years of expansion? Also what raid type will be used? Is Exchange going on the DC or the Application server? Does the server meet Exchange requirements? These are things you need to preconfigure and preplan before just jumping into a project like this.
There are also other items you want to keep on your mind such as: backup software, backup storage, disaster recovery plan and failover\redundancy plans, as if that DC goes offline for any reason (like bad windows updates or hardware failure etc...), your network is at a stand still with no DNS and AD profiles etc...
There is a few others to think of but I do know the budget for the project so I'm only going to advise the necessities.
3) IS it possible if so please guide me how, ???
See #2 and also articles below:
Creating a new Domain Controller:
Configuring DNS (skip down to "configuring dns" as DNS role is installed when you install Active Directory role)
Installing DHCP (you will have to configure it after, which is something custom to your network)
Installing Exchange (not 100% perfect guide but its pretty close. Good enough to get you going)
Configuring Application server (simply join the application server to your new domain and install\configure application role if need be)
4) ANy license available for Server 2016?? when is it going to be launched??
Yes, it will most likely use the same schema Server 2013 used for it's licensing. However, I would recommend to the client that it is not a smart idea to jump onto a brand new OS right when it has been released. A lot of the time there are issues that get through in testing and leak through into the production release. It is smarter to wait a few months for patches to be released before jumping onto the new OS. This goes for both servers and workstation OS's.
I believe it is set to be release next quarter.
5) Please tell how to make one server Domain controller? and other Application and how to get users access? and how to connect both?
All this is very dependent on the network and application being used. The above guides should be enough to get a new domain up and running, however the application server is in your hands. Once it is deployed you will need to figure out what type of application is being used (as a stated above, is it a TS based application or a network/workstation install based application) and configure accordingly.
These questions you are asking is what us Network Engineers do at $175+/hr for a living. It is not as simple as "follow X guide" because every network is different and the requirements to run that network must be tailored to work for them.
The above should give you a good start, but it is no where at 100% of everything you will need. There are tons of unanswered questions that will be between you and the client to figure out which will be the best configuration for their network.
I hope that was enough to get you started!