[SalesForce] Governor Limits for Asynchronous Methods

a). No, when you execute a test class, it runs every method in the test class.

b). Governor limits are reset for each test method. In addition, some governor limits are reset in between the Test.startTest() and Test.stopTest() functions used commonly in test methods.

Here's a good guide to getting started with test methods: An Introduction to Apex Code Test Methods

You may have to limit the number of records you create, even down to one per type. If it's still hitting the limit at that point, you're pretty much SOL. As a last resort, you can use SeeAllData=true so that you aren't hitting triggers. Test.loadData won't really help as it still fires triggers.

One solution you can implement as you build out your org (which may be more difficult to implement with existing functionality) is to build trigger stop flags into your handler pattern. My template looks something like:

public with sharing class LeadTriggerHandler
{
    @TestVisible static Boolean bypassTrigger = false;

    final List<Lead> newRecords;
    final Map<Id, Lead> oldMap;
    public LeadTriggerHandler(List<Lead> newRecords, Map<Id, Lead> oldMap)
    {
        this.newRecords = newRecords;
        this.oldMap = oldMap;
    }

    public void beforeInsert()
    {
        if (bypassTrigger) return;
        //LeadSerivices.method1(newRecords);
    }
    public void afterInsert()
    {
        if (bypassTrigger) return;
        //LeadSerivices.method2(newRecords);
    }

    public void beforeUpdate()
    {
        if (bypassTrigger) return;
        //LeadSerivices.method1(newRecords);
    }
    public void afterUpdate()
    {
        if (bypassTrigger) return;
        //LeadSerivices.method3(newRecords);
    }
}

Then in your test you can just do:

LeadTriggerHandler.bypassTrigger = true;
insert new Lead(/*data*/);
LeadTriggerHandler.bypassTrigger = false;

This flagging strategy can dramatically streamline your tests, and can be implemented in a variety of ways. The key is that the flag is static, though I think it is important to keep it private if at all possible.