W3C Validators Errors and Warnings

Hello, I am noticing that the number of W3C validators errors and warnings are increasing on the website. I have trying to fix the following errors but can’t seem to fix a solution. Can anyone help? The website is http://www.businessplanmyway.com…thank you!!

1. Line 122, Column 11: Element hgroup not allowed as child of element header in this context. (Suppressing further errors from this subtree.)
<hgroup>
Content model for element header:
Flow content, but with no header, footer, or main element descendants.

2. Line 122, Column 11: The hgroup element is obsolete. To mark up subheadings, consider either just putting the subheading into a p element after the h1-h6 element containing the main heading, or else putting the subheading directly within the h1-h6 element containing the main heading, but separated from the main heading by punctuation and/or within, for example, a span class=”subheading” element with differentiated styling. To group headings and subheadings, alternative titles, or taglines, consider using the header or div elements.
<hgroup>

3. Line 124, Column 30: Empty heading.
<h2 id=”site-description”></h2>
✉
4. Line 279, Column 7: Element style not allowed as child of element div in this context. (Suppressing further errors from this subtree.)
<style>
Contexts in which element style may be used:
If the scoped attribute is absent: where metadata content is expected.
If the scoped attribute is absent: in a noscript element that is a child of a head element.
If the scoped attribute is present: where flow content is expected, but before any other flow content other than inter-element whitespace and style elements, and not as the child of an element whose content model is transparent.
Content model for element div:
Flow content.

5. Line 287, Column 473: Bad value 55px for attribute height on element img: Expected a digit but saw p instead.
… Twitter’ height=’55px’ width=’55px’ /><a href=”https://www.facebook.com/p…
Syntax of non-negative integer:
One or more digits (0–9). For example: 42 and 0 are valid, but -273 is not.