Your question is rather difficult to answer in detail because the answer would cover lengthy discussion of the many points you raised but I will try to cover the core concepts here. I will start by:
Also, I am thinking of learning PHP simultaneously. Because I feel learning some other language will might help me understand C# better. Is this the right thing?
Well, if you are a person with average IQ, it is hard to learn PHP and Microsoft Stack (C#, EF, LINQ, ADO), ...etc + different frameworks, ..., all together at the same time. The above statement is my opinion and is not scientific fact of course.
So, first, determine what you want to do with all of this. Are you building a system for yourself, do you want a job as a professional developer, etc. This is very important.
Next, I assume that you should start by focusing on ONE technology stack (or event 1 tool).
Assuming you go with Microsoft, you then have to pick an application model (eg. Silverlight, WPF, ASP.NET or Windows Forms). This is very important too because each of those technologies have its own framework and you need to be familiar with other related technology to the selected application model (e.g. HTML is needed for ASP.NET but not for WPF).
Now we come to the database part. You either pick no-sql, XML only or SQL RDBMS (like most do)
Let's say you go with SQL RDBMS, you still have a combination of choices to make regarding how to access this data from your code:
- ADO.NET (with or without LINQ)
- EF with LINQ
- Use of a 3rd party ORM (I will not get into this here because it is a very lengthy subject)
ADO.NET worked for the early days of .NET and represents an important foundation for data access, so learning it is important.
I don't want to use Entity Framework and LINQ when I don't understand them and what do they offer.
If your goal is to be a professional developer with Microsoft Technologies, you need to know LINQ (and I suggest you add EF as well) to some extent even if you don't directly use them in your current project. Knowing these technologies will open a wider market than knowing ADO.NET only.
"At Microsoft’s November 2009 Professional Developer Conference, the legendary Don
Box, a Distinguished Engineer at Microsoft, said, “If you’re a .NET developer Entity
Framework is where we’re going. We’re there. Get on board, it’s time."
"The ADO.NET Entity Framework has shifted into becoming Microsoft’s core data
access platform for building .NET applications" - From the book: Programming Entity Framework by Julia Lerman.
The EF with LINQ allows you to program using your business objects instead of programming against data tables directly. Some of the Other benefits are listed here:
Entity Framework Features
New Features in Entity Framework 4.0 (V2)