Link for Enhanced Email:
https://play.google.com/store/apps/details?id=com.qs.enhancedemail
Too bad EE is no longer under active development as a standalone app, it is very good. EE has been sold to Boxer, who makes a popular iOS email app. They are working on the Android version of Boxer, supposedly combining features of Boxer and EE. Possibly when that is ready it will have the features you're looking for.
To setup including a logo or other image in your signature you must:
1. Make the image file available on a publicly accessible host - your website for example. I use Google Drive, as in the example code below. A simple Google search will find several examples how to do that, so I won't go into that here. Edit the host address below as necessary.
2. Set EE to compose email as HTML.
3. Edit the code below as necessary.
4. Copy and paste the corrected code in the Signature box of EE.
Code:
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=ISO-8859-1">
<title></title>
</head>
<body bgcolor="#FFFFFF" text="#000000">
<img src="https://googledrive.com/host/0B8s06zNeRuYFU0R0OWppQXJZU2M/?Your_Logo.jpg"><br></div>
<font face="DejaVu Sans"><font face="DejaVu Serif">Your Company<br>
Description<br>
Your Name<br>
Phone or text: 555.555.5555<br>
Web: yourwebsite.com<br>
</font></font>
</body>
</html>
I told you it takes some work. But when done, it's pretty cool. And you can add the hosted image to your Gmail webmail (do it in Gmail Settings in a browser) or use the same HTML signature file with a desktop email client. Nice!