Programming Forms in HTML

Hello. I am currently learning HTML in my CSIS class. As part of an assignment, we have to add a form to collect information about the user. I got the basic code down, thanks to a couple of websites, but I would also like to add some "advanced" features.

1.) For my form, I ask the user for his/her birthdate. I decided to use drop down boxes for the month and day. I was wondering, can I limit the selection of days to the month? Example: If the month of October is selected, the user can only choose 1 though 30 for the day instead of the full 31 days that I have programmed in the code.

2.) For the year that the person was born, I have a text box. How can I limit the value that can be entered no more than 4 digits?

3.) Right now, I have the following in the code for my form: <form action="MAILTO:myemail@somewhere.com" method="post" enctype="text/plain"> With this code, upon clicking submit, Outlook Express opens with a "New Message" window. Is it possible to program it so that when submit is clicked, that it will send the information directly to my inbox without opening Outlook Express?

Also, I have one other question. When using an unordered list, I know that there are different types of bullets that can be used like circles or squares. Can gif files be used as well?

Below is the code I have thus far for my form. I replaced my e-mail address with a fake one for security purposes.
Thanks for the help.
Robert2513

<form action="MAILTO:myemail@somewhere.com" method="post" enctype="text/plain">
<u>Tell me About Yourself</u>
<br>
Name:<br>
<input type="text" name="name" size="30">
<br>

E-Mail Address:<br>
<input type="text" name="mail" size"30">
<br>

Birthdate:<br>
<select name="birthmonth">
<option value="January">January
<option value="February">February
<option value="March">March
<option value="April">April
<option value="May">May
<option value="June">June
<option value="July">July
<option value="August">August
<option value="September">September
<option value="October">October
<option value="November">November
<option value="December">December
</select>

<select name="birthday">
<option value="1">1
<option value="2">2
<option value="3">3
<option value="4">4
<option value="5">5
<option value="6">6
<option value="7">7
<option value="8">8
<option value="9">9
<option value="10">10
<option value="11">11
<option value="12">12
<option value="13">13
<option value="14">14
<option value="15">15
<option value="16">16
<option value="17">17
<option value="18">18
<option value="19">19
<option value="20">20
<option value="21">21
<option value="22">22
<option value="23">23
<option value="24">24
<option value="25">25
<option value="26">26
<option value="27">27
<option value="28">28
<option value="29">29
<option value="30">30
<option value="31">31
</select>

<input type="text" name="Year" size="20">
<br>

Major:<br>
<input type="text" name"major" size="20">
<br>

<br><br>
<input type="submit" value="Send">
<input type="reset" value="Reset">