It all depends on the requirements you are working with.
If you can be SURE that all the fields to test are there (or if this is not the point of your test because someone else is testing this), you shouldn't bother testing it.
If you are testing the whole thing, meaning that everything a) works and b) works as intended, then i suggest you split your tests in two - one part that simply checks the form, content etc of the page and it's elements and a part two that considers everything's there and tests if it functions correctly. Part two will then contain field verifications like "enter invalid email", "enter letters in a phone number field", "leave a mandatory field blank" etc.
For practical reasons i try to keep my tests as short as possible and as specific as possible. Here's a few reasons why:
If you find a bug, your whole test case will be "failed", it's clearer later on to find what's working and what not if the test case doesn't test many functionalities that are not tightly connected. If you take your need for example, if you test the existence AND the functionality of your fields in one test and one step doesn't work your test will be "failed" but by glancing at your test campaign you won't be able to know which part has a bug without going deeper and examining the execution in detail.
If you have to come back to re-test something after it's been fixed you won't have to go through dozens of steps before you are able to verify the correction.
People tend to lose focus if they have to execute a very long test case, they might forget what's going on, etc.
Of course, this depends a lot on the task at hand, some things require much longer/complex test cases, others can be very simple.