No. You do not claim yourself as a dependent. Head of Household is a filing status. See this TurboTax support FAQ for HOH - https://ttlc.intuit.com/questions/1894553-do-i-qualify-for-head-of-household
When filing you receive a personal exemption as the taxpayer. If you have a dependent then they also have a personal exemption. If there are no other dependents and you are Single or considered unmarried then there will only be two exemptions on the tax return.
No. You do not claim yourself as a dependent. Head of Household is a filing status. See this TurboTax support FAQ for HOH - https://ttlc.intuit.com/questions/1894553-do-i-qualify-for-head-of-household
When filing you receive a personal exemption as the taxpayer. If you have a dependent then they also have a personal exemption. If there are no other dependents and you are Single or considered unmarried then there will only be two exemptions on the tax return.
If you are filling in a W-4 then YES you may claim 3 ALLOWANCES if that is what the "worksheet" portion of the form says.
Exemptions are what are on the tax return and do not need to be the same number as the Allowances claimed on the W-4.